Harry's percentage scores for the three tests are 60%, 60%, and 40% respectively. Hence the average percentage is (60+60+40)/3 = 160/3 = 53.33. A common mistake here is to simply take the average of 60% and 40% and incorrectly reach the solution 50%. Since there are two tests in which Harry scores 60%, we take a weighted average, wherein we add 60+60+40 and divide by 3. (d)