Prove that if BA=I then BA=AB.

Answers

Answer 1

Answer with Step-by-step explanation:

Since we have given that

[tex]BA=I[/tex]

As we know that

AA⁻¹ = I (A is invertible matrix)

Multiplying A⁻¹ on the both the sides:

[tex]BAA^{-1}=IA^{-1}\\\\B=A^{-1}[/tex]

Using the above result, we get that

[tex]BA=I=AA^{-1}\\\\BA=AB[/tex]

Therefore, BA = AB

Hence, proved.


Related Questions

A net force of 24 N is acting on a 4.0-kg object. Find the acceleration in m/s 6m/s^2

Answers

Step-by-step explanation:

mass of the object=m=4 kg

the net force exerted on it=F=24N=kgm/s²

the acceleration of the object=a=?

formula for calculating the acceleration=

F=ma

plug in the values

24kgm/s²=4kga

divide each side by 4

24kgm/s²/4 kg=4kga/4kg

a=6m/s²

Final answer:

The acceleration of the 4.0-kg object with a net force of 24 N is 6 m/s².

Explanation:

Acceleration: To find the acceleration, we use Newton's Second Law: F = ma. Given a net force of 24 N on a 4.0-kg object, the acceleration can be calculated as follows:

a = F/m = 24 N / 4.0 kg = 6 m/s²

Therefore, the acceleration of the object is 6 m/s².

A survey among freshman at a certain university revealed that the number of hours spent studying before final exams was normally distributed with mean 25 and standard deviation 15. A sample of 36 students was selected. What is the probabiliy that the average time spent stydying for the sampe was between 28.2 and 30 hours

Answers

Answer: 0.0775

Step-by-step explanation:

Given : Mean : [tex]\mu = 25[/tex]

Standard deviation : [tex]\sigma =15[/tex]

Sample size : [tex]n=36[/tex]

Since its normal distribution , then the formula to calculate the z-score is given by :-

[tex]z=\dfrac{x-\mu}{\dfrac{\sigma}{\sqrt{n}}}[/tex]

For x= 28.2 hours

[tex]z=\dfrac{28.2-25}{\dfrac{15}{\sqrt{36}}}=1.28[/tex]

For x= 30 hours

[tex]z=\dfrac{30-25}{\dfrac{15}{\sqrt{36}}}=2[/tex]

The P- value = [tex]P(1.28<z<2)[/tex]

[tex]=P(z<2)-P(z<1.28)= 0.9772498-0.8997274=0.0775224\approx0.0775[/tex]

Hence, the probabiliy that the average time spent stydying for the sampe was between 28.2 and 30 hours = 0.0775

The probability that the average time spent studying for the sample was between 28.2 and 30 hours is calculated as 0.0775 or 75 %.

To calculate the probability that the average time spent studying for the sample was between 28.2 and 30 hours, we use the normal distribution and standardize the sample means to a z-score.

Given the population mean (μ) is 25 hours, the population standard deviation (σ) is 15 hours, and the sample size (n) is 36, the standard error of the mean (SEM) is σ/√n which is 15/6 = 2.5 hours.

The z-scores for 28.2 and 30 hours are calculated as (X - μ)/(SEM).

Z for 28.2 hours = (28.2 - 25)/2.5 = 1.28
Z for 30 hours = (30 - 25)/2.5 = 2

Now we can look up these z-scores in the standard normal distribution table (or use calculator/software) to find the probabilities for these z-scores and then find the probability that lies between them by subtracting the two.

Example: Let's assume the probability corresponding to z=1.28 is 0.8997 and to z=2 is 0.9772.

The probability that the sample mean lies between 28.2 and 30 hours is:

P(1.28 < Z < 2) = P(Z < 2) - P(Z < 1.28)

= 0.9772 - 0.8997
= 0.0775

Hence, there is a 7.75% probability that the sample mean is between 28.2 and 30 hours.

10 men and 12 women will be seated in a row of 22 chairs. What is the probability that all men will be seated side by side in 10 consecutive positions? 1/C(22, 10) 10!/C(22, 10) 10!/22! 10! middot 12!/22! 10! middot 13!/22!

Answers

Answer:

The correct option is 4.

Step-by-step explanation:

It is given that 10 men and 12 women will be seated in a row of 22 chairs.

Total possible ways to arrange n terms is n!.

Similarly,

Total possible ways to place 22 people on 22 chairs = 22!

[tex]\text{Total outcomes}=22![/tex]

It is given that all men will be seated side by side in 10 consecutive positions.

Total possible ways to place 10 people on 10 chairs = 10!

Let 10 men = 1 unit because all men will be seated side by side in 10 consecutive positions. 12 women = 12 units because women can any where.

Total number of units = 12 + 1 = 13.

Total possible ways to place 13 units = 13!

Total possible ways to place 10 men and 12 women, when all men will be seated side by side in 10 consecutive positions is

[tex]\text{Favorable outcomes}=10!\cdot 13![/tex]

The probability that all men will be seated side by side in 10 consecutive positions

[tex]P=\frac{\text{Favorable outcomes}}{\text{Total outcomes}}=\frac{10!\cdot 13!}{22!}[/tex]

Therefore the correct option is 4.

The functions q and r are defined as follows.
q(x) = -2x +1
r(x) = 2x^2 - 1
Find the value of .
q(r(4))

Answers

Answer:

q(r(4)) = -61

Step-by-step explanation:

q(x) = -2x +1

r(x) = 2x^2 - 1

q(r(4))

First find r(4)

f(4) = 2 (4)^2 -1

      = 2 *16 -1

      = 32-1

     = 31

Then put this value in for x in q(x)

q(r(4)) = q(31) = -2(31)+1

                     = -62+1

                     = -61

Answer:

The value of q( r(4) ) = -61

Step-by-step explanation:

It is given that,

q(x) = - 2x +1

r(x) = 2x^2 - 1

To find the value of q(r(4))

r(x) = 2x^2 - 1

r(4) = 2( 4^2) - 1  [Substitute 4 instead of x]

 = 2(16) - 1

 = 32 - 1 = 31

q( x ) = -2x +1

q( r(4) ) = q(31)        [Substitute 31 instead of x)

 =  (-2*31) +1

 = -62 + 1 = -61

Therefore the  value of q(r(4)) = -61

Add the Base 2 numbers: 11,110,110 +101,101,111

Answers

Answer:

100000

Step-by-step explanation:

I did the operations in the picture, you only have to know that 0+1=01, 1+1=10

and 1+1+1=11.

Now, I don't know if you need to calculate the total add, I calculated it.

In this case, you need to know that 1+1+1+1=100.

The sum of the two Base 2 numbers is: [tex]\[ {10001001_2} \][/tex].

The sum of the given Base 2 (binary) numbers is calculated as follows:

 11,110,110

+ 101,101,111

Starting from the rightmost digit (least significant bit) and moving left, we add the digits:

- In the rightmost column, 0 + 1 = 1.

- In the next column, 1 + 1 = 10 (which is 0 in the current column and carry over 1 to the next column).

- Continuing this process, we add the digits along with any carry from the previous column.

 Let's continue the addition:

 11,110,110

+ 101,101,111

--------------

 1,000,1001

Here's the step-by-step process:

- 0 + 1 = 1 (no carry).

- 1 + 1 = 10 (0 in this column, carry 1).

- 1 + 0 + 1 (carry) = 10 (0 in this column, carry 1).

- 1 + 1 + 1 (carry) = 11 (1 in this column, carry 1).

- 1 + 0 + 1 (carry) = 10 (0 in this column, carry 1).

- 1 + 1 + 1 (carry) = 11 (1 in this column, carry 1).

- 1 + 0 + 1 (carry) = 10 (0 in this column, carry 1).

- 1 + 1 + 1 (carry) = 11 (1 in this column, carry 1).

- 1 + 0 + 1 (carry) = 10 (0 in this column, carry 1).

- 1 + 1 + 1 (carry) = 11 (1 in this column, carry 1).

- Finally, we have a carry of 1 that we add to the leftmost digit, giving us 1 + 1 = 10 (0 in this column, carry 1).

Since there are no more digits to add, we write down the 1 at the beginning:

 1,000,1001

Therefore, the sum of the two Base 2 numbers is:

[tex]\[ {10001001_2} \][/tex].

Audrey Graco plans to conduct book signings in several cities to promote her new novel. She wishes to visit Knoxville, Chattanooga, Chapel Hill, Charlotte, Raleigh, and Richmond. How many different ways can she visit each of these cities and return to her starting point in Wilmington? O A. 720 O B. 30 O C. 29 O D. 120 Click to select vour answer

Answers

Final answer:

Audrey can visit the six cities in which she plans to conduct book signings and return to her starting point in 720 different ways. This is because of the mathematical principle of permutations.

Explanation:

Audrey's problem deals with permutations because the order of the places she visits matters. In general, the number of ways to arrange 'n' items (in Audrey's case, 'n' cities) in a specific order is given by 'n things taken n at a time' which is mathematically represented as n! (n factorial). In this case, Audrey is visiting 6 cities (Knoxville, Chattanooga, Chapel Hill, Charlotte, Raleigh, and Richmond), and then returning to her original city, Wilmington. So, the number of ways she can visit these cities can be represented as 6!, which equals 720.

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A bag contains 6 red apples and 5 yellow apples. 3 apples are selected at random. Find the probability of selecting 1 red apple and 2 yellow apples.

Answers

Final answer:

To solve the problem, first calculate all possible combinations of selecting 3 apples from 11. Then calculate the favorable combinations, which include selecting 1 red apple (from 6 available) and 2 yellow apples (from 5 available). Divide these values to get the probability.

Explanation:

The topic at hand is one of probability, more specifically, it's a problem of combinations in probability. The bag contains a total of 11 apples (6 red and 5 yellow). When 3 apples are chosen, we want to find the probability that 1 is red and 2 are yellow.

First, calculate the total number of ways to choose 3 apples from 11, which is denoted as '11 choose 3', using combination formula C(n,r) = n! / [r!(n - r)!]. Then, consider the number of favorable outcomes: choosing 1 red apple from 6 (denoted as '6 choose 1') and 2 yellow apples from 5 (denoted as '5 choose 2'). Multiply these two results because we choose '1 red' and '2 yellow', using the rule of product. Calculate these individual results and then divide the favorable outcomes by the total outcomes to get the required probability.

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A floor refinishing company charges $1.83 per square foot to strip and refinish a tile floor for up to 1000 square feet. There is an additional charge of $350 for toxic waste disposal for any job which includes more than 150 square feet of tile.

A) Express the cost, y, of refinishing a floor as a function of the number of square feet, x, to be refinished.
b) Graph the function, give the domain and range.

Answers

Answer:

Here x represents the number of square feet to be refinished and y represents the cost of refinishing the floor,

Given,

The cost of a tile floor for up to 1000 square feet is $1.83 per square,

So, the cost of x square feet of tile = 1.83x for x ≤ 1000

⇒ y = 1.83x for x ≤ 1000

Since, there is an additional charge of $350 for toxic waste disposal for any job which includes more than 150 square feet of tile.

That is, y = 1.83x + 350, for x > 150

So, y must be 1.83x for x ≤ 150.

A) Hence, the function that express the cost, y, of refinishing a floor as a function of the number of square feet, x, to be refinished, is,

[tex]y=\begin{cases}1.83x & \text{ if } 0\leq x\leq 150 \\ 1.83x+350 & \text{ if } 150< x\leq 1000\end{cases}-----(1)[/tex]

B) The domain of the function =  all possible value of x

⇒ Domain = 0 ≤ x ≤ 1000

Range = All possible value of y,

Since, the range of function y=1.83x, 0≤ x ≤ 150 is [0, 274.5]

While the range of function y = 1.83x + 350, for x > 150 is (624.5, 2180]

Hence, the range of the function (1) = [0, 274.5]∪(624.5, 2180]

Final answer:

The cost of refinishing a floor can be expressed as a piecewise function based on the number of square feet to be refinished. The domain of the function is all real numbers, and the range is all real numbers greater than or equal to 0.

Explanation:

Let x represent the number of square feet to be refinished.

For x ≤ 150, the cost of refinishing a floor is simply $1.83 per square foot. So, the cost function, y, for x ≤ 150 is y = 1.83x.

For x > 150, there is an additional charge of $350 for toxic waste disposal. So, the cost function, y, for x > 150 is y = 350 + 1.83x.

The overall cost function, y, is given by:

y = 1.83x, for x ≤ 150

y = 350 + 1.83x, for x > 150

The domain of the function is all real numbers, since any positive number of square feet can be refinished. The range of the function is all real numbers greater than or equal to 0, since the cost cannot be negative.

Solve the following inequalities:

A) 2w + 17 ˃ -4w -25

B) 2.3 + 0.6t ˂ 2 + 0.8t

C) Determine if – 3.5 and 10 make the inequalities in Parts A) and B) true or not. Check both numbers in both inequalities. Show your work.

Answers

Answer:

A) w > -7

B) 1.5 < t

C) -3.5 makes A) true and B) false

    10 makes both inequalities true

Step-by-step explanation:

The idea of these exercises is to clear our variable, we need it to be alone on one side of the inequality

A) 2w + 17 ˃ -4w -25

First, we will put together on one side the terms with a w and on the other the terms without w.

For that, we have to add 4w - 17 on both sides

2w + 17 + 4w - 17 ˃ -4w -25 + 4w - 17 (Notice that 17-17=0 and -4w+4w=0, so we don't have to write them below)

2w + 4w > -25 - 17

Now we can sum the terms (we didn't do it before because we can't sum a term with a w with one without it)

6w > -42

We divide by 6 on both sides and we have

6/6w > -42/6

w > -7

B) 2.3 + 0.6t ˂ 2 + 0.8t

We start as before; in this case we have to put together the terms with a t (our variable changes name but the idea is the same)

We will add -2 - 0.6t on both sides

2.3 + 0.6t -2 - 0.6t ˂ 2 + 0.8t -2 - 0.6t  

2.3 - 2 < 0.8t - 0.6t

Now we sum the terms  

0.3 < 0.2t

We divide by 0.2 on both sides and we have

0.3/0.2 < 0.2/0.2t

1.5 < t

C) Let's check -3.5 on both inequalities:

We have to replace the variable by -3.5:

2*(-3.5) + 17 ˃ -4*(-3.5) -25 (remember that if there is no sign between a number and a variable, it means that is a multiplication)

Now we just solve the calculation

-7 + 17 > 14 -25

10 > -11

That's true, so -3.5 makes the inequality true.

Now, in the other inequality, we replace the t by -3.5 and solve as before

2.3 + 0.6*(-3.5) ˂ 2 + 0.8*(-3.5)

2.3 - 2.1 < 2 - 2.8

0.2 < -0.8

That's false because we are saying that a negative number is bigger than a positive one, so -3.5 makes the inequality not true.

  Now we do the same with 10 in both inequalities:

   2*10 + 17 ˃ -4*10 -25

   20 + 17 > -40 -25

   37 > - 65

   It's true!

   2.3 + 0.6*10 ˂ 2 + 0.8*10

   2.3 + 6 < 2 + 8

   8.3 < 10

   It's true!

(×-5) second power equals 3​

Answers

Answer: [tex]x_1=6.73\\\\x_2=3.26[/tex]

Step-by-step explanation:  

Given the following expression:

[tex](x-5)^2=3[/tex]

And knowing that:

[tex](a\±b)^2=a^2-2ab+b^2[/tex]

We get:

[tex]x^2-2(x)(5)+5^2=3\\\\x^2-10x+25=3[/tex]

Move the 3 to the left side of the equation:

[tex]x^2-10x+25-3=0\\\\x^2-10x+22=0[/tex]

Apply the Quadratic formula:

[tex]x=\frac{-b\±\sqrt{b^2-4ac} }{2a}[/tex]

In this case:

[tex]a=1\\b=-10\\c=22[/tex]

Substituting values into the Quadratic formula, we get:

[tex]x=\frac{-(-10)\±\sqrt{(-10)^2-4(1)(22)} }{2(1)}\\\\\\x_1=6.73\\\\x_2=3.26[/tex]

Identify the radius and center.

x^2 + y^2 - 2x + 4y - 11 = 0

Answers

Hello!

The answer is:

Center: (1,-2)

Radius: 4 units.

Why?

To solve the problem, using the given formula of a circle, we need to find its standard equation form which is equal to:

[tex](x-h)^{2}+(y-k)^{2}=r^{2}[/tex]

Where,

"h" and "k"are the coordinates of the center of the circle and "r" is its radius.

So, we need to complete the square for both variable "x" and "y".

The given equation is:

[tex]x^2+y^2-2x+4y-11=0[/tex]

So, solving we have:

[tex]x^2+y^2-2x+4y=11[/tex]

[tex](x^2-2x+(\frac{2}{2})^{2} )+(y^2+4y+(\frac{4}{2})^{2})=11+(\frac{2}{2})^{2} +(\frac{4}{2})^{2}\\\\(x^2-2x+1)+(y^2+4y+4)=11+1+4\\\\(x^2-1)+(y^2+2)=16[/tex]

[tex](x^2-1)+(y^2-(-2))=16[/tex]

Now, we have that:

[tex]h=1\\k=-2\\r=\sqrt{16}=4[/tex]

So,

Center: (1,-2)

Radius: 4 units.

Have a nice day!

Note: I have attached a picture for better understanding.

For a dosage of x cubic centimeters​ (cc) of a certain​ drug, assume that the resulting blood pressure B is approximated by B (x) = 0.06 x^2 - 0.3 x^3 . Find the dosage at which the resulting blood pressure is maximized. Round to two decimal places.

Answers

Answer:

The number of dosage is 0.13.

Step-by-step explanation:

Here, the given function that represents the blood pressure,

[tex]B(x)=0.06x^2 - 0.3x^3[/tex]

Where, x is the number of dosage in cubic centimeters​,

Differentiating the above function with respect to x,

[tex]B'(x)=0.12x-0.9x^2[/tex]

For maximum or minimum blood pressure,

[tex]B'(x)=0[/tex]

[tex]0.12x-0.9x^2=0[/tex]

[tex]-0.9x^2=-0.12x[/tex]

[tex]x=\frac{0.12}{0.9}=\frac{2}{15}[/tex]

Again differentiating B'(x) with respect to x,

[tex]B''(x)=0.12-1.8x[/tex]

Since, at x = 2/15,

[tex]B''(\frac{2}{15})=0.12-1.8(\frac{2}{15})=0.12-0.24=-0.12=\text{Negative value}[/tex]

So, at x = 2/15 the value of B(x) is maximum,

Hence, the number of dosage at which the resulting blood pressure is maximized = 2/15 = 0.133333333333 ≈ 0.13

Final answer:

The maximum blood pressure results from a dosage of approximately 0.13 cubic centimeters, based on the mathematical model given in the problem.

Explanation:

To find the maximum blood pressure using the formula B (x) = 0.06 x^2 - 0.3 x^3, we need to first find the derivative of this equation, as the maximum point on any curve happens when its derivative equals zero.

First, differentiate B(x) with respect to x: B'(x) = 2*0.06x - 3*0.3x^2 = 0.12x - 0.9x^2 Next, set this derivative equal to zero and solve for x: 0 = 0.12x - 0.9x^2 0 = x(0.12 - 0.9x) So x = 0 or x = 0.12/0.9 = 0.133 Lastly, we need to determine if these x-values give a maximum or minimum in B(x). We do this by either taking the second derivative of B(x) or by testing points on either side of the x-values we found. If we find the second derivative, we find that B''(x) = 0.12 -1.8x, which is negative for x = 0.133. This means that the blood pressure is maximized at an x-value of 0.133 cc, or, rounded to two decimal places, 0.13 cc

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Find a power series representation for the function. (Give your power series representation centered at x = 0.)f(x) = x3x2 + 1f(x) = ∞n = 0 Determine the interval of convergence. (Enter your answer using interval notation.)

Answers

I suppose you mean

[tex]f(x)=\dfrac{x^3}{x^2+1}[/tex]

Recall that for [tex]|x|<1[/tex], we have

[tex]\dfrac1{1-x}=\displaystyle\sum_{n=0}^\infty x^n[/tex]

Then

[tex]\dfrac1{1+x^2}=\dfrac1{1-(-x^2)}=\displaystyle\sum_{n=0}^\infty(-x^2)^n=\sum_{n=0}^\infty(-1)^nx^{2n}[/tex]

which is valid for [tex]|-x^2|=|x|^2<1[/tex], or more simply [tex]|x|<1[/tex].

Finally,

[tex]f(x)=\displaystyle\frac{x^3}{x^2+1}=\sum_{n=0}^\infty(-1)^nx^{2n+3}[/tex]

1) Homer and Marge have purchased a home for $189 000. The real estate agent informs them that homes in their area have generally depreciated by 11% every six years. Based on this, how much should they be able to sell their home for in 15 years? (3 points)

Answers

Answer:

They should be able to sell their home for $149706.9

Step-by-step explanation:

Let's first understand the situation.

There is an initial value for the house which is $189000. However, this value varies every 6 years because of a 11% depreciation of the total value.

Because the depreciation is not executed during the 6 years in a constant way, but instead after the whole 6 years have passed, then we can calculate how many depreciations will be applied within the next 15 years:

total years/years needed for depreciation=15years/6years=2.5

The above means that only 2 depreciations are going to be applied. Remember that depreciation is only applied if the whole 6 years have passed.  

Now, after the first 6 years the depreciation (D) is:

D = 0.11 * $189000 = $20790,

which means that the value of the house will be:

(initial value) - D = $189000 - $20790 = $168210

Now, after the following 6 years, first 12 years, the depreciation (D) is:

D = 0.11 * $168210 = $18503.1,

which means that the value of the house will be:

(initial value) - D = $168210 - $18503.1 = $149706.9

In conclusion, in 15 years from now, they should be able to sell their home for $149706.9

Consider the integral 8 (x2+1) dx 0 (a) Estimate the area under the curve using a left-hand sum with n = 4. 250 Is this sum an overestimate or an underestimate of the true value? overestimate underestimate (b) Estimate the area under the curve using a right-hand sum with n = 4. 248

Answers

Answer:

  (a) 120 square units (underestimate)

  (b) 248 square units

Step-by-step explanation:

(a) left sum

See the attachment for a diagram of the areas being summed (in orange). This is the sum of the first 4 table values for f(x), each multiplied by 2 (the width of the rectangle). Quite clearly, the curve is above the rectangle for the entire interval, so the rectangle area underestimates the area under the curve.

  left sum = 2(1 + 5 + 17 + 37) = 2(60) = 120 . . . . square units

(b) right sum

The right sum is the sum of the last 4 table values for f(x), each multiplied by 2 (the width of the rectangle). This sum is ...

  right sum = 2(5 +17 + 37 +65) = 2(124) = 248 . . . . square units

Please help me with this

Answers

Answer:

The correct answer is first option

24

Step-by-step explanation:

From the figure we get, mAXM = 72° and  m<AMR = 38°

Also it is given that, all triangles are isosceles triangles and

m<FXA = 96°

To find the measure of <FXM

From the figure we get,

m<FXA =  m<AXM + m<FXM

m<FXM = m<FXA - m<AXM

 = 96 - 72

 = 24

Therefore the  correct answer is first option

24

Write an equation of the horizontal asymptote for this function. Also, interpret what this asymptote means in the context of the problem (in terms of the fish population and the number of years since the fish were introduced into the lake.)

Answers

Answer:

Step-by-step explanation:

First, finding the horizontal asymptote:

[tex]\lim_{t \to \infty} = \frac{200+40t}{1+0.05t} = \frac{\frac{200}{t} 40 }{\frac{1}{t} 0.05} = 800[/tex]

In the context of the problem, the horizontal asymptote speaks about where the population of the fish is headed and capped.

In order to start a small business, a student takes out a simple interest loan for $3000.00 for 9 months at a rate of 11.75%. a. How much interest must the student pay? b. Find the future value of the loan. a. The amount of interest is $ . (Round to the nearest cent as needed.) b. The future value is $ (Round to the nearest cent as needed.)

Answers

Answer: (a) $264.375 ⇒ Amount of Interest

(b) Future Value = $3264.375

Step-by-step explanation:

(a) Principal amount = $3000

Time period = 9 months

Interest rate = 11.75%

Simple interest(SI) = principal amount × rate of interest (i) × time period

                              = 3000 × [tex]\frac{11.75}{100}[/tex] × [tex]\frac{9}{12}[/tex]

                              = 3000 × 0.1175 × 0.75

                               = $264.375 ⇒ Amount of Interest

(b) Future value of loan = principal amount + interest amount

                                        = 3000 + 264.375

                                        = 3264.375

A thief steals an ATM card and must randomly guess the correct seven​-digit pin code from a 4​-key keypad. Repetition of digits is allowed. What is the probability of a correct guess on the first​ try?

Answers

The probability of guessing the correct seven-digit pin code on the first try is very low, approximately 0.000024%.

Given that,

A thief steals an ATM card.

The thief must guess the correct seven-digit pin code.

The pin code is entered using a 4-key keypad.

The probability of guessing the correct seven-digit pin code on the first try depends on a few factors.

To break it down,

if the thief has a 4-key keypad and repetition of digits is allowed, that means there are four options for each digit.

So, there are a total of 4⁷ (4 raised to the power of 7) possible combinations.

Since the thief is trying to guess the correct pin code on the first try, there is only one correct combination out of the total possible combinations.

Therefore,

The probability of guessing the correct pin code on the first try would be 1 out of 4⁷, or approximately 0.00000024, or 0.000024%.

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The probability of randomly guessing a 7-digit PIN from a 4-key keypad is 1 in 16,384. This equals approximately 0.000061 or 0.0061%. Each digit has 4 possible options, and there are 7 digits in total.

The probability of guessing a seven-digit PIN code correctly from a 4-key keypad (where repetition of digits is allowed) can be calculated as follows:

Since each of the 7 digits in the PIN can be any of 4 possible digits (0 through 3), the total number of possible combinations is calculated by raising the number of choices per digit to the power of the number of digits:

→ Total possible combinations = 4^7

= 4⁷

= 16384

Therefore, the probability of guessing the correct PIN on the first try is the reciprocal of the total number of possible combinations:

→ Probability of a correct guess = 1 / 16384

Hence, the probability is approximately 0.000061 or 0.0061%.

Solve the following equations: (a) x^11=13 mod 35 (b) x^5=3 mod 64

Answers

a.

[tex]x^{11}=13\pmod{35}\implies\begin{cases}x^{11}\equiv13\equiv3\pmod5\\x^{11}\equiv13\equiv6\pmod7\end{cases}[/tex]

By Fermat's little theorem, we have

[tex]x^{11}\equiv (x^5)^2x\equiv x^3\equiv3\pmod5[/tex]

[tex]x^{11}\equiv x^7x^4\equiv x^5\equiv6\pmod 7[/tex]

5 and 7 are both prime, so [tex]\varphi(5)=4[/tex] and [tex]\varphi(7)=6[/tex]. By Euler's theorem, we get

[tex]x^4\equiv1\pmod5\implies x\equiv3^{-1}\equiv2\pmod5[/tex]

[tex]x^6\equiv1\pmod7\impleis x\equiv6^{-1}\equiv6\pmod7[/tex]

Now we can use the Chinese remainder theorem to solve for [tex]x[/tex]. Start with

[tex]x=2\cdot7+5\cdot6[/tex]

Taken mod 5, the second term vanishes and [tex]14\equiv4\pmod5[/tex]. Multiply by the inverse of 4 mod 5 (4), then by 2.

[tex]x=2\cdot7\cdot4\cdot2+5\cdot6[/tex]

Taken mod 7, the first term vanishes and [tex]30\equiv2\pmod7[/tex]. Multiply by the inverse of 2 mod 7 (4), then by 6.

[tex]x=2\cdot7\cdot4\cdot2+5\cdot6\cdot4\cdot6[/tex]

[tex]\implies x\equiv832\pmod{5\cdot7}\implies\boxed{x\equiv27\pmod{35}}[/tex]

b.

[tex]x^5\equiv3\pmod{64}[/tex]

We have [tex]\varphi(64)=32[/tex], so by Euler's theorem,

[tex]x^{32}\equiv1\pmod{64}[/tex]

Now, raising both sides of the original congruence to the power of 6 gives

[tex]x^{30}\equiv3^6\equiv729\equiv25\pmod{64}[/tex]

Then multiplying both sides by [tex]x^2[/tex] gives

[tex]x^{32}\equiv25x^2\equiv1\pmod{64}[/tex]

so that [tex]x^2[/tex] is the inverse of 25 mod 64. To find this inverse, solve for [tex]y[/tex] in [tex]25y\equiv1\pmod{64}[/tex]. Using the Euclidean algorithm, we have

64 = 2*25 + 14

25 = 1*14 + 11

14 = 1*11 + 3

11 = 3*3 + 2

3 = 1*2 + 1

=> 1 = 9*64 - 23*25

so that [tex](-23)\cdot25\equiv1\pmod{64}\implies y=25^{-1}\equiv-23\equiv41\pmod{64}[/tex].

So we know

[tex]25x^2\equiv1\pmod{64}\implies x^2\equiv41\pmod{64}[/tex]

Squaring both sides of this gives

[tex]x^4\equiv1681\equiv17\pmod{64}[/tex]

and multiplying both sides by [tex]x[/tex] tells us

[tex]x^5\equiv17x\equiv3\pmod{64}[/tex]

Use the Euclidean algorithm to solve for [tex]x[/tex].

64 = 3*17 + 13

17 = 1*13 + 4

13 = 3*4 + 1

=> 1 = 4*64 - 15*17

so that [tex](-15)\cdot17\equiv1\pmod{64}\implies17^{-1}\equiv-15\equiv49\pmod{64}[/tex], and so [tex]x\equiv147\pmod{64}\implies\boxed{x\equiv19\pmod{64}}[/tex]

Problem 4. Let m and n be two integers. Show that m^3- n^3 is even if and only if m n is even.

Answers

Answer:

The expression [tex]m^3-n^3[/tex] is even if both variables (m and n) are even or both are odd

Step-by-step explanation:

Let's remember the logical operations with even and odd numbers

odd*odd=odd

even*even=even

odd*even=even

odd-odd=even

even-even=even

even-odd=odd

Now, the original expression is:

[tex]m^3-n^3[/tex] which can be expressed as:

[tex](m*(m*m))-(n*(n*n))[/tex]

If m and n are both odd, then:

[tex](m*(m*m))=odd*(odd*odd)=odd*(odd)=odd[/tex]

[tex](n*(n*n))=odd*(odd*odd)=odd*(odd)=odd[/tex]

Then, [tex](m*(m*m))-(n*(n*n))=odd-odd=even[/tex]

If m and n are both even, then:

[tex](m*(m*m))=even*(even*even)=odd*(even)=even[/tex]

[tex](m*(m*m))=even*(even*even)=odd*(even)=even[/tex]

Then, [tex](m*(m*m))-(n*(n*n))=even-even=even[/tex]

Finally if one of them is even, for example m, and the other is odd, for example n, then:

[tex](m*(m*m))=even*(even*even)=odd*(even)=even[/tex]

[tex](n*(n*n))=odd*(odd*odd)=odd*(odd)=odd[/tex]

Then, [tex](m*(m*m))-(n*(n*n))=even-odd=odd[/tex]

In conclusion, the expression [tex]m^3-n^3[/tex] is even if both variables (m and n) are even or both are odd. If one of them is even and the other one is odd, then the expression is odd.

Which graph represents the function f(x) = –x^2 + 5?

Answers

Answer:

See below.

Step-by-step explanation:

This will be a parabola with axis of symmetry x = 0 and will open downwards.

The vertex will be at the point (0 , 5). The graph will intersect the x axis  at

(-√5, 0) and (√5, 0).

Answer:

its a

Step-by-step explanation:

The following data summarizes results from 941 pedestrian deaths that were caused by accidents. If one of the pedestrian deaths is randomly selected, find the probability that the pedestrian was intoxicated or the driver was intoxicated.
Pedestrian Pedestrian
Intoxicated Not intoxicated
Driver Intoxicated 56 71
Driver Not intoxicated 292 522

Answers

Answer:

P=0.3698  or 36.98%

Step-by-step explanation:

Complete the table by adding the totals to each column and row.

                                Pedestrian     Pedestrian

                                Intoxicated    Not intoxicated Totals

Driver Intoxicated           56                     71               127

Driver Not intoxicated   292                   522             814

Totals                            348                    593             941

The probability that the pedestrian was intoxicated or the driver was intoxicated is the opposite event of neither of them was intoxicated.  The total of cases when neither of them was intoxicated is 593. So the probability is:

P1=593/941=0.6302

The probability of the opposite event is one minus the probability calculated:

P=1-0.6302=0.3698

And this is the probability that the pedestrian was intoxicated or the driver was intoxicated.

Individuals who have a certain gene have a 0.46 probability of contracting a certain disease. Suppose that 913 individuals with the gene participate in a lifetime study. What is the standard deviation of the number of people who eventually contract the disea

Answers

Answer: 15.06

Step-by-step explanation:

Given : The number of individuals participated in a lifetime study :[tex]n=913[/tex]

The probability of individuals with certain gene of contracting a certain disease :[tex]p= 0.46[/tex]

Now, the standard deviation of the number of people who eventually contract the disease is given by :_

[tex]\sigma =\sqrt{np(1-p)}\\\\=\sqrt{913\times0.46(1-0.46)}=15.059521904\approx15.06[/tex]

Hence, the  the standard deviation of the number of people who eventually contract the disease = 15.06

You obtain a loan of $7500 at 16.5% compounded monthly. If you make $300 payments monthly, what is the term of the loan? Find the size of the concluding payment if: a. the last full payment is increased to pay off the loan b. the last smaller payment is made one month after the last full payment.

Answers

Answer:

last installment is $540

Step-by-step explanation:

principal amount (p) = $7500

rate (r) = 16.5 %

installment = $300

to find out

full payment is increased to pay off the loan and the last smaller payment is made one month after the last full payment

solution

we know monthly installment is $300 so amount will be paid i.e.

amount = $300×12×N ..............1

here N is no of installment

and we know amount formula i.e.

amount = principal ( 1+r/100)^N

put amount value and principal rate

300×12×N = 7500 ( 1+16.5/100)^N

(3600 ×N ) / 7500 = 1.165^N

0.48N = 1.165^N

by the graphical we will get N = 3.65

so 3.65 year

so as that put N in equation 1 we get

amount = $300×12× 3.65

amount = $13140

we can say there are 43 installment so remaining money is  $13140 - ($300 × 43 installment )

i.e. = $240 and last installment will be $300 + $240 = $540

so last installment is $540

Problem 4. Solve the following counting problems. (a) How many committees of size 6 can be formed by a club consisting of 15 people?

Answers

Answer:

5005

Step-by-step explanation:

In the question we have to form a committee of six from a club of consisting of 15 people.

This a simple case of selection of six people from a group of 15 people.

which can be done in

[tex]^{15}C_6= \frac{15!}{6!\times9!}=5005[/tex]

hence, the number of ways of forming committees of size six from a club of 15 members= 5005

Q2. On a cold day, hailstones fall with a velocity of (2i− 6k) m s−1 . If a cyclist travels through the hail at 10i ms−1 , what is the velocity of the hail relative to the cyclist? At what angle are the hailstones falling relative to the cyclist

Answers

Answer:[tex]-8\hat{i}-6\hat{k}[/tex]

[tex]\theta =\tan^{-1}\left ( \frac{3}{4} \right )[/tex]

Step-by-step explanation:

Given

Velocity of hailstones fall[tex]\left ( V_h\right )=2\hat{i}-6\hat{k}[/tex] m/s

Velocity of cyclist [tex]\left ( V_c\right )=10\hat{i}[/tex] m/s

Therefore

Velocity of hail with respect to cyclist[tex]\left ( V_{hc}\right )[/tex]

[tex]V_{hc}=V_h-V_c[/tex]

[tex]V_{hc}=2\hat{i}-6\hat{k}-10\hat{i}[/tex]

[tex]V_{hc}=-8\hat{i}-6\hat{k}[/tex]

and angle of hails falling relative to the cyclist is given by

[tex]\theta =\tan^{-1}\left ( \frac{3}{4}\right )[/tex]

[tex]\theta [/tex] is the angle made with the vertical

Ted is not particularly creative. He uses the pickup line​ "If I could rearrange the​ alphabet, I'd put U and I​ together." The random variable x is the number of girls Ted approaches before encountering one who reacts positively. Determine whether the table describes a probability distribution. If it​ does, find its mean and standard deviation. If a probability distribution is not​ given, identify the requirements that are not satisfied.
x P(x)
1 0.001
2 0.025
3 0.101
4 0.246
5 0.503

Answers

Answer:

Not a probability distribution

Step-by-step explanation:

The given table doesn't describe a probability distribution as in order for the given distribution to be a probability distribution the sum of probabilities is required to be equal to one.

Here,

Sum of probabilities = 0.001+0.025+0.101+0.246+0.503 = 0.876

The sum of probabilities is not equal to one.

Therefore, the given distribution is not a probability distribution ..

In a class of 40 students, everyone has either a pierced nose or a pierced ear. The professor asks everyone with a pierced nose to raise his or her hand. Eight hands go up. Then the professor asked everyone with a pierced ear to do likewise. This time there are 35 hands raised. How many students have piercings both on their ears and their noses?

Answers

Answer:

3 students

Step-by-step explanation:

If everyone in the class has either a pierced nose or ear, we just simply have to add up the total number of hands raised and minus the number of students in the class.

35+8=43

43-40=3

3 students have both a pierced nose and pierced ear.

Giovanni and Jean started a 120-mile bicycle race at the same time. Giovanni cycled at 23.9 miles per hour while Jean cycled at 24 miles per hour. When Jean crossed the finish line, how many miles was Giovanni from the finish line? Express your answer as a decimal to the nearest tenth.

Answers

Answer:

Giovanni was 0.5 miles from the finish line

Step-by-step explanation:

This is a problem of movement with constant velocity.

For this kind of problems, generally it is enough to remember the definition of average velocity v:

[tex]v=\frac{x}{t}[/tex]

Where x is the change in position that took place in an interval t.

First, find the time that Jean, who cycled at 24 miles per hour, spent on the race:

Isolating t from the last equation,

[tex]t=\frac{x}{v}[/tex], and replacing the data for Jean movement:

[tex]t=\frac{120}{24}=5h[/tex]

Second, find what was the distance that Giovanni had cycled when Jean crossed the line:

[tex]x=v*t\\ x=23.9*5=119.5[/tex]

When Jean crossed the line he had cycled 120 miles, and Giovanni 119.5; so Giovanni was 0.5 miles from the finish line.

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