Answer to Question #119277 in Statistics and Probability for Amoah Henry

Question

Emmanuel is given a multiple-choice 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

n=10

Probability of getting a correct answer is $\frac {1}{5}$ =0.2

This is a binomial probability case

P(X=x) =${n \choose x } p^x q^{n-x}$

$P(X\geq 6)=\sum_{i=6}^{10} 0.2^x 0.8^{10-x}$

=0.00637