Question

A student takes a 19 question multiple choice quiz with 4 choices for each question. If the student guesses at random on each question, what is the probability that the student gets more than 2 questions correct?

Answer 1

Here we have:

n = 19

p = 0.25

Binomial distribution:

P( X > 2 ) = 1 - P( X <= 2)

P( X > 2 ) = 1 - P( X <= 2)

= 1 - 0.1113

= 0.8887

The probability that the student gets more than 2 questions correct = 0.8887