According to the National Telecommunication and Information Administration, 56.5% of U.S. households owned a computer in 2001. What is the probability that of three randomly selected U.S. households at least one owned a computer in 2001?
A) 91.8%
B) 82.0%
C) 56.5%
D) 43.5%
E) 18.0%

Question

Quizplus · Accepted Answer

The probability that at least one household owned a computer is easier to calculate by finding the probability that none of the three households owned a computer and subtracting this from 1. The probability that a single household did not own a computer is 1 - 0.565 = 0.435. Therefore, the probability that none of the three households owned a computer is 0.435^3 = 0.082. Subtracting this from 1 gives 1 - 0.082 = 0.918 or 91.8%.