Question

just answer nuber 18 please

Discrete Binomial Distributions: Assume that you are taking a multiple choice test that you have not studied for! The test only has 9 questions and each question has four possible answers. You plan to randomly guess on all 9 questions and the probability you get one correct is the same for all questions. 17. What is the probability you get the first question correct? A. 0.25 B. 0.50 C. 0.75 D. 1.00 18. Using the random guess strategy, how many questions do you expect to get correct on the exam? A. 2.0 B. 2.25 C. 2.5 D. 3.0

Answer 1

It is given that there are four options for each of the 9 questions, and probability of choosing the right option is the same for all the 9 questions. Among the four alternatives 1 is surely correct. So, for one question the probability of choosing the correct option is ¼ or 0.25.

So, out of the 9 questions the expected number of questions that one expects to answer correctly is 9 × 0.25 = 2.25. So, option B is correct.