Find the sum of the infinite geometric series 1 + 1/3 + 1/9 + 1/27 + ...
Correct: E
The sum of an infinite geometric series with first term a and common ratio r (where |r| < 1) is a/(1-r). In this case, a=1 and r=1/3. So the sum is 1/(1-1/3) = 1/(2/3) = 3/2.