A test consists of 10 multiple choice questions, each with five possible answers, one of which is correct. To pass the test a student must get 60% or better on the test. If a student randomly guesses, what is the probability that the student will pass the test?

Respuesta :

Answer:

0.006369

Step-by-step explanation:

Given that a test consists of 10 multiple choice questions, each with five possible answers, one of which is correct.

By mere guessing p = probability for a right answer = 1/5 =0.20

There are two outcomes and each question is independent of the other.

X no of questions right is Bin (10,0.20)

the probability that the student will pass the test

= prob of getting more than 60%

=[tex]P(X\geq 6)[/tex]

=0.006369

Probability of an event is measure of its chance of occurrence. The probability that the student will pass the test is 0.0064 approx

How to find that a given condition can be modeled by binomial distribution?

Binomial distributions consists of n independent Bernoulli trials.

Bernoulli trials are those trials which end up randomly either on success (with probability p) or on failures( with probability 1- p = q (say))

Suppose we have random variable X pertaining binomial distribution with parameters n and p, then it is written as

[tex]X \sim B(n,p)[/tex]

The probability that out of n trials, there'd be x successes is given by

[tex]P(X =x) = \: ^nC_xp^x(1-p)^{n-x}[/tex]

For the given condition, we can model the situation by binomial distribution where each question's answering is a Bernoulli trial, independent of other question's answer, and answering correct is tagged as success.

P(Answering correct) = probability of success = p = 1/5 (as each option is equally likely, and one correct option is there per 5 option available

Probability of failure = q = 1-p = 4/5

Number of trials = 10 (since 10 Multiple Choice Questions are there)

Thus, if we take X = number of questions answered correctly, then:

[tex]X \sim B(n=10, p = 1/5 = 0.2)[/tex]

For getting at least 60% marks, student needs to answer 60% of 10 questions correctly, which is 6 questions (at least).

P(Student will pass the test) = P(X ≥ 6)

[tex]P(X \geq 6) =P(X = 6) + P(X = 7) + P(X = 8) + P(X=9)+P(X = 10)\\\\P(X \geq 6) = \sum_{i=6}^{10} \: ^{10}C_i p^i q^{10-i} = \sum_{i=6}^{10} \: ^{10}C_i (0.2)^i (0.8)^{10-i} \approx 0.0064[/tex]

Thus, the probability that the student will pass the test is 0.0064 approx


Learn more about binomial distribution here:

https://brainly.com/question/13609688