The probability that a student will graduate from a college is 0.4. If 3 students are selected from the college, what is the probability that at least one student will graduate?
Worked solution (try it first)
The probability that a student does not graduate is 1−0.4=0.6.
The probability that none of the 3 graduates is 0.63=0.216.
At least one is everything except none: 1−0.216=0.784≈0.78, option C.