Hi! I need to know if I would be correct on this...

In a multiple choice quiz there are 5 questions and 4 choices for each question (a, b, c, d). Robin has not studied for the quiz

Ahat [919]

Answer:

a) There is a 18.75% probability that the first question that she gets right is the second question.

b) There is a 65.92% probability that she gets exactly 1 or exactly 2 questions right.

c) There is a 10.35% probability that she gets the majority of the questions right.

Step-by-step explanation:

Each question can have two outcomes. Either it is right, or it is wrong. So, for b) and c), we use the binomial probability distribution to solve this problem.

Binomial probability distribution

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

$P(X = x) = C_{n,x}.\pi^{x}.(1-\pi)^{n-x}$

In which $C_{n,x}$ is the number of different combinatios of x objects from a set of n elements, given by the following formula.

$C_{n,x} = \frac{n!}{x!(n-x)!}$

And $\pi$ is the probability of X happening.

In this problem we have that:

Each question has 4 choices. So for each question, Robin has a $\frac{1}{4} = 0.25$ probability of getting ir right. So $\pi = 0.25$ . There are five questions, so $n = 5$ .

(a) What is the probability that the first question she gets right is the second question?

There is a 75% probability of getting the first question wrong and there is a 25% probability of getting the second question right. These probabilities are independent.

So

$P = 0.75(0.25) = 0.1875$

There is a 18.75% probability that the first question that she gets right is the second question.

(b) What is the probability that she gets exactly 1 or exactly 2 questions right?

This is: $P = P(X = 1) + P(X = 2)$

$P(X = x) = C_{n,x}.\pi^{x}.(1-\pi)^{n-x}$

$P(X = 1) = C_{5,1}.(0.25)^{1}.(0.75)^{4} = 0.3955$

$P(X = 2) = C_{5,2}.(0.25)^{2}.(0.75)^{3} = 0.2637$

$P = P(X = 1) + P(X = 2) = 0.3955 + 0.2637 = 0.6592$

There is a 65.92% probability that she gets exactly 1 or exactly 2 questions right.

(c) What is the probability that she gets the majority of the questions right?

That is the probability that she gets 3, 4 or 5 questions right.

$P = P(X = 3) + P(X = 4) + P(X = 5)$

$P(X = x) = C_{n,x}.\pi^{x}.(1-\pi)^{n-x}$

$P(X = 3) = C_{5,3}.(0.25)^{3}.(0.75)^{2} = 0.0879$

$P(X = 4) = C_{5,4}.(0.25)^{4}.(0.75)^{1} = 0.0146$

$P(X = 5) = C_{5,5}.(0.25)^{5}.(0.75)^{0} = 0.001$

$P = P(X = 3) + P(X = 4) + P(X = 5) = 0.0879 + 0.0146 + 0.001 = 0.1035$

There is a 10.35% probability that she gets the majority of the questions right.

6 0

3 years ago

A new operation is defined by a△b=a^2-b/b-a^2. 4△3.

dmitriy555 [2]

As the new mathematical operation is defined by a△b=a^2-b/b-a^2, the value of 4△3 using the same operation will be 4△3 = -1

As per the question statement, we are given a new mathematical operation a△b=a^2-b/b-a^2 and we are supposed to find the value of 4△3 using the same operation.

Given, a△b=a^2-b/b-a^2

now 4△3 = (4^2-3) / (3-4^2)

4△3 = (16-3) / (3-16)

4△3 = 13 / -13

4△3 = -1

Hence, as the new mathematical operation is defined by a△b=a^2-b/b-a^2, the value of 4△3 using the same operation will be 4△3 = -1.

Mathematical operation: An operator in mathematics is often a mapping or function that transforms components of one space into elements of another.

To learn more about mathematical operation, click on the link given below:

brainly.com/question/8959976

#SPJ1

8 0

1 year ago

The length of the rectangular tennis court at wimbledon is 6 feet longer than twice the width. if the court's perimeter is 240 f

KATRIN_1 [288]

Length (L): 2w + 6

width (w): w

Perimeter (P) = 2L + 2w

240 = 2(2w + 6) + 2(w)

240 = 4w + 12 + 2w

240 = 6w + 12

228 = 6w

38 = w

Length (L): 2w + 6 = 2(38) + 6 = 76 + 6 = 82

Answer: width = 38 ft, length = 82 ft

8 0

3 years ago

7 copies of the sum of 8 fifths and 4

Serggg [28]

So what you would do is 8/5 + 4 x 7 = 26.9
then you round it to 30

7 0

3 years ago

125x80 solve the question

Lelechka [254]

Answer:

The answer is of the following is 10,000

5 0

3 years ago

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