Richard has just been given an l0-question multiple-choice quiz in his history class. Each question has five answers, of which only one is correct, Since Richard has not attended a class recently, he doesn't know any of the answers, Assuming that Richard guesses on all 10 questions. Find the indicated probabilities.
A) What is the probability that he will answer all questions correctly?
B) What is the probability that he will answer all questions incorrectly?
C) What is the probability that he will answer at least one of the questions correctly?
Then use the fact that P(r1) = 1 P(r = 0).
D) What is the probability that Richard will answer at least half the questions correctly?

Answers

Answer 1

Answer:

a) 0.0000001024 probability that he will answer all questions correctly.

b) 0.1074 = 10.74% probability that he will answer all questions incorrectly

c) 0.8926 = 89.26% probability that he will answer at least one of the questions correctly.

d) 0.0328 = 3.28% probability that Richard will answer at least half the questions correctly

Step-by-step explanation:

For each question, there are only two possible outcomes. Either he answers it correctly, or he does not. The probability of answering a question correctly is independent of any other question. This means that we use the binomial probability distribution to solve this question.

Binomial probability distribution

The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

[tex]P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}[/tex]

In which [tex]C_{n,x}[/tex] is the number of different combinations of x objects from a set of n elements, given by the following formula.

[tex]C_{n,x} = \frac{n!}{x!(n-x)!}[/tex]

And p is the probability of X happening.

Each question has five answers, of which only one is correct

This means that the probability of correctly answering a question guessing is [tex]p = \frac{1}{5} = 0.2[/tex]

10 questions.

This means that [tex]n = 10[/tex]

A) What is the probability that he will answer all questions correctly?

This is [tex]P(X = 10)[/tex]

[tex]P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}[/tex]

[tex]P(X = 10) = C_{10,10}.(0.2)^{10}.(0.8)^{0} = 0.0000001024[/tex]

0.0000001024 probability that he will answer all questions correctly.

B) What is the probability that he will answer all questions incorrectly?

None correctly, so [tex]P(X = 0)[/tex]

[tex]P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}[/tex]

[tex]P(X = 0) = C_{10,0}.(0.2)^{0}.(0.8)^{10} = 0.1074[/tex]

0.1074 = 10.74% probability that he will answer all questions incorrectly

C) What is the probability that he will answer at least one of the questions correctly?

This is

[tex]P(X \geq 1) = 1 - P(X = 0)[/tex]

Since [tex]P(X = 0) = 0.1074[/tex], from item b.

[tex]P(X \geq 1) = 1 - 0.1074 = 0.8926[/tex]

0.8926 = 89.26% probability that he will answer at least one of the questions correctly.

D) What is the probability that Richard will answer at least half the questions correctly?

This is

[tex]P(X \geq 5) = P(X = 5) + P(X = 6) + P(X = 7) + P(X = 8) + P(X = 9) + P(X = 10)[/tex]

In which

[tex]P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}[/tex]

[tex]P(X = 5) = C_{10,5}.(0.2)^{5}.(0.8)^{5} = 0.0264[/tex]

[tex]P(X = 6) = C_{10,6}.(0.2)^{6}.(0.8)^{4} = 0.0055[/tex]

[tex]P(X = 7) = C_{10,7}.(0.2)^{7}.(0.8)^{3} = 0.0008[/tex]

[tex]P(X = 8) = C_{10,8}.(0.2)^{8}.(0.8)^{2} = 0.0001[/tex]

[tex]P(X = 9) = C_{10,9}.(0.2)^{9}.(0.8)^{1} \approx 0[/tex]

[tex]P(X = 10) = C_{10,10}.(0.2)^{10}.(0.8)^{0} \approx 0[/tex]

So

[tex]P(X \geq 5) = P(X = 5) + P(X = 6) + P(X = 7) + P(X = 8) + P(X = 9) + P(X = 10) = 0.0264 + 0.0055 + 0.0008 + 0.0001 + 0 + 0 = 0.0328[/tex]

0.0328 = 3.28% probability that Richard will answer at least half the questions correctly


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Step-by-step explanation:

Answer:

wheel: radius=3/2  diameter=3  circumference=3pi

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Step-by-step explanation:

30. President Ronald Reagan earned a yearly salary of 2 x 10^5 dollars as
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Answers

Answer:

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Step-by-step explanation:

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Answers

Answer:

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Step-by-step explanation:

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Answers

5 = (20%) x (total)

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If Matrix A is 3 x 4, and Matrix B is 4 x 2, what is the size of matrix BA? If BA is undefined, please state so.

Answers

Answer:

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Step-by-step explanation:

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Answer:

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Step-by-step explanation:

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Answers

Answer:

43.96

Step-by-step explanation:

Well, the first step is finding out the diameter. And then the basic outline is d x 3.14. So I simply just punched in 14 x 3.14 in my calculator.

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Circumference of the circle

= 2πr

= 2π(14/2)

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Answers

Answer:

Step-by-step explanation:

a)

2.64÷3.3  ( said  2.64 divided by 3.3)

3.3√2.64  ( yes I know it's not the division sign but it's as close as we can get)

2.64 / 3.3

All three representations  are the same. each say  divide 2.64 by 3.3. If you're thinking that last one looks more like a fraction, you're right, but.. that's also what that means.   I'm showing these different ways to express the idea of division b/c it's part of what is involved with showing the work and understanding it.

so, to do the above let's move the decimal point to the right .. and do we want to move it one or two places.  :?  one because of 3.3 or two , because of 2.64, well we want to move it so we don't have to think about it in the problem... so move it the biggest amount that you need to, get the the decimil out of both numbers.. since the 2.64 needs two moves to the right of the decimal... use 100 times  to move it 2 places, If you needed 3 then use 1000, 4 , 10,000 ect ect... see the pattern?

so

100(3.3 √ 2.64 )

move the decimal point in both 2 places right

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I put the extra zeros in, just so you can see the decimal easy.  The zeros to the right of the decimal make no difference here.

now I'll know to put the number that I use to divde with above the zero,  of 264.0  .. and i'll think about how many times 3 goes into 26 ,without going over.  3*8 = 24 so I want an 8

    ↓ ←   ←  ← 0.8

330.0 √ 264.0      ( multiply  8 * 330 = 2640 )

    ↓ →   -264 .0      ( subtract 2640 from the number above )

                       0

you are done with that one, since there is zero left over and   0.8 is the answer

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  ↓  ←  ←  1.2

270 √ 324.0

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Answers

Answer:

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Step-by-step explanation:

First,

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Then -(minus) from 100

Answer:

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Answers

Answer:

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Answers

Answer:

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Step-by-step explanation:

to this ‘Great Man Theory’ it can be said that Franklin Delano Roosevelt upheld his victorious and highly regarded government through means of social, economic and political reforms, as well as ambitious personal and strategic decisions that have successfully remained influential to American society today and maintained his image as a prominent historic leader.

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Answers

Answer:

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Answers

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Step-by-step explanation:

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Answers

Answer:

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Step-by-step explanation:

I can't do all of them but I'll do the first 2:

1.

let w be the width of the rectangle

Then the length would be 2w + 2

Using those, the perimeter would be:

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solving:

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This means the length would be:

[tex]2(60)+2\\120 + 2\\122[/tex]

2.

let a be the number of adult tickets

let s be the number of student tickets

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The total number of tickets is 12, so:

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Answers

Answer:

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Step-by-step explanation:

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Answers

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A

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Answers

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A

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Answer:

34.54 ft2

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Answers

Answer:

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Step-by-step explanation:

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Answers

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Answers

Answer:

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Step-by-step explanation:

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Answers

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2 x (13)

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Find the following for this parabola:
A) The vertex:
B) The vertical intercept is the point
C) Find the coordinates of the two z intercepts of the parabola and write them as a list, separated by
commas:
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Answers

Answer:

Step-by-step explanation:

f(x)  = 2x² + 14x - 4

= 2(x² + 7x) - 4

= 2(x² +7x + 3.5²) - 2(3.5²) - 4

= 2(x+3.5)² - 28.5

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The x-intercepts are the values of x for which y=0.

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A school buys 1,950 pencils. The pencils are sold in boxes, with 30 pencils in each box. If each box costs $4.05, what is the total cost, in dollars, that the school will pay for the pencils?

Answers

The answer is
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