Question

A multiple choice test has 30 questions. each question has five possible answers, of which one is correct. if a student guesses on every question, find the probability of getting exactly 12 correct.

Answer 1

Total number of questions = 30
Probability of getting an answer right = 1/5
Probability of getting an answer wrong = 4/5
Number of questions to be correct = 12
Number of questions to be wrong = 30 - 12 = 18


`\left(\begin{array}{c}30\\12\end{array}\right) \left(\begin{ (1)/(5) }\right)^(12)\left(\begin{ (4)/(5) }\right)^(18) = 0.06`