Question

A student takes random guesses at each problem on a 15-problem quiz. Each problem is a multiple choice question with 5 possible solutions. What is the probability that the student gets a B (80.0% - 89.5%) on the quiz?

Answer 1

here this is binomial distribution with paramter n=15 and p=probability of guessing one question right=1/5 =0.2

probability that the student gets a B =P(getting 12 or 13 question right)

=P(X=12)+P(X=13)=

=9.54*10^-7+0.55*10^-7 =0.000001009