Question

Find the indicated binomial probability. A multiple choice test has 30 questions, and each has four possible answers, of which one is correct. If a student guesses on every question, find the probability of getting exactly 12 correct.

Answer 1

0.02906

Explanation:

number of questions =30

getting exactly right : 12

30C12 the number of possibilities

probability to get it right (1/4)^12

probability of failure =1-1/4=(3/4)^18 ( 18 = 30 questions -12 right )

P(12)=30C12*(1/4)^12*(3/4)^18=0.02906

hope it helps