Mark M. answered 08/17/19
Retired college math professor. Extensive tutoring experience.
The probability of r successes in n trials is nCr(p)r(q)n-r, where p is the probability of success on a given trial and q = 1-p.
In this problem, n = 6, r = 3, p = q = 0.5
So, P(3 successes in 6 trials) = 6C3(0.5)3(0.5)3 = 20(1/64) = 20/64 = 5/16 = 0.3125 ≈ 31.3%