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A student takes an exam containing 1414 multiple choice questions. The probability of choosing a correct answer by knowledgeable

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Answer:

0.0082 = 0.82% probability that he will pass

Step-by-step explanation:

For each question, there are only two possible outcomes. Either the students guesses the correct answer, or he guesses the wrong answer. The probability of guessing the correct answer for a question is independent of other questions. So 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.

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

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

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

And p is the probability of X happening.

In this problem we have that:

$n = 14, p = 0.3$ .

If the student makes knowledgeable guesses, what is the probability that he will pass?

He needs to guess at least 9 answers correctly. So

$P(X \geq 9) = P(X = 9) + P(X = 10) + P(X = 11) + P(X = 12) + P(X = 13) + P(X = 14)$

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

$P(X = 9) = C_{14,9}.(0.3)^{9}.(0.7)^{5} = 0.0066$

$P(X = 10) = C_{14,10}.(0.3)^{10}.(0.7)^{4} = 0.0014$

$P(X = 11) = C_{14,11}.(0.3)^{11}.(0.7)^{3} = 0.0002$

$P(X = 12) = C_{14,12}.(0.3)^{12}.(0.7)^{2} = 0.000024$

$P(X = 13) = C_{14,13}.(0.3)^{13}.(0.7)^{1} = 0.000002$

$P(X = 14) = C_{14,14}.(0.3)^{14}.(0.7)^{0} \cong 0$

$P(X \geq 9) = P(X = 9) + P(X = 10) + P(X = 11) + P(X = 12) + P(X = 13) + P(X = 14) = 0.0066 + 0.0014 + 0.0002 + 0.000024 + 0.000002 = 0.0082$

0.0082 = 0.82% probability that he will pass

6 0

3 years ago

Darren's town voted on a new speed limit. 10% of the 20 votes were in favor of the new speed limit. How many votes were in favor

Westkost [7]

10% of 20
20/10 = 2
2 votes were in favour

3 0

3 years ago

Three ballet dancers are positioned on stage. Greta is straight behind Bryan and directly left of Alice. If Bryan and Greta are

Neko [114]

Answer:

12

Step-by-step explanation:

4 0

2 years ago

Which is the equation of the parabola?

mestny [16]

Answer:

y = -1/20(x + 3)²

Step-by-step explanation:

<u>Consider the parent function:</u>

y = x²

The graph of the function open up and the vertex is at the origin, the point (0, 0)

Now, if it opens down, it means it is a reflection of the parent function over x axis, hence it has a negative coefficient, the function becomes:

y = -x²

The vertex is shifted to the point (-3, 0). It means the function also translated left by 3 units, the function becomes:

y = -(x + 3)²

<u>Since all the options have 1/20 as a coefficient, our function is:</u>

y = -1/20(x + 3)²

This is option B

6 0

3 years ago

The cost of manufacturing lawn mowers is $12,320 in overhead costs and $396 per lawn mower in production costs. Marketing studie

ANEK [815]

Hello, your cost function will be 12,320+(x*396). Your revenue function will be (452x) and the profit function will be (452x)-12,320+(x*396). I hope this helps, have a good day.

6 0

3 years ago

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