MATH
posted by STEPHANIE on .
If 20% of population have blue eyes, and 5 people are selected at random, what is the probability that at least 4 of them have blue eyes?
HOW DO I FIND THE SOLUTION TO THIS PROBLEM?

Prob(blue eyes) = .2
Prob(not blue eyes)= .8
prob( at least 4 of 5 have blue eyes)
= prob(exactly 4 of 5 have blue eyes) + prob(exactly 5 of 5 have blue eyes)
= C(5,4)(.2)^4 (.8) + C(5,5)(.2)^5
= 5(.0016)(.8) + 1(.00032)
= .000672