Problem 2CQQ

There are 100 questions from an SAT test, and they are all multiple choice with possible answers of a, b, c, d, e. For each question, only one answer is correct. Find the mean number of correct answers for those who make random guesses for all 100 questions.

Answer :

Step 1 of 1

We know that

There are 100 questions from an SAT test, and they are all multiple choice with possible answers of a, b, c, d, e. For each question, only one answer is correct.

So, n = 100

p =

P =

p = 0.2

Let the mean number of correct answers for those who make random guesses for all 100 questions.

Then the mean of the formula is

μ=np

μ =(100) (0.2)

μ = 20

Therefore the mean number of correct answers for those who make random guesses for all 100 questions is μ =156