binomial distribution

Question

Find the probability of at least 3 successes in six trials of a binomial experiment in which the probability of success is 50% Round to the nearest tenth of a percent.

Answer 1

There's a formula for the probability of having exactly k successes in n trials of a binomial experiment with probability p of success. You should look it up in your textbook (or other learning material). It's

P(X = k) = (_nC_k)p^k(1-p)^(n-k)

"At least 3 successes" means you just calculate the values for 3, 4, 5 or 6 successes and add them up. Or if you prefer, you could total the values for 0,1 or 2 successes and then subtract this sum from 1.