Question

A multiple choice test consisting of 10 questions. each question has four choices. a,b,c, and d tell how you would find the probability of guessing at least one correct answer, without the use of binomial probability formula. what rule would your use to simplify your solution?

Answer 1

Each question has 4 choices out of which one is correct. The probability of correct answer is

p = 1/4 = 0.25

The probability that one answer is incorrect is

P(incorrect)= 1-p = 0.75

Let us first find the probability that out of 10, all 10 answers are incorrect. Since each question is independent from other so by the multiplication rule the probability that all questions are incorrect is

By the complement rule, the probability that at least one question is correct is

P(at least one correct) = 1 - 0.0563 = 0.9437