Question

Emmanuel is given a multiple choice question exam with ten questions and each question with five possible answers. He decided to guess randomly for each question. What is the probability that he will get at least six questions correct.

Answer 1

This is a binomial distribution with $p=0.2,\;n=10.$

$P(X\ge6)=\sum_{i=6}^{10}C_{10}^i0.2^i(1-0.2)^{10-i}=0.0064.$