Question 20

This is a very basic percent question with actual numbers. There are many percent questions on the GMAT without actual numbers. It is often the absence of actual numbers that makes these questions difficult.

The most important word in the question is "remaining." See the fourth line of the question.

Mathematical Solution

The total time is 50 minutes. A total of (5 + 10) 15 minutes is spent not working on the project. This means that 50 - 15 = 35 minutes were spent discussing the project. Basically, this question is asking: what percent of 50 is 35? In other words:

convert the fraction 35/50 into percent form.

(On the GMAT it is very important to know how to convert fractions, to decimals, to percents and vice-versa.)

35/50 = 70/100 = 70%

Hence, the answer is (C).

Multiple Choice Is Your Friend Solution

Let's say all you can understand is greater or less than 50%. 50% of 50 is 25. Since 35 is greater than 25, the answer must exceed 50%. Hence, (E) is wrong.

Let's say all you can understand is greater or less than 25%. 25% of 50 is 12.5. 3 times 12.5 = 37.5. Since 37.5 is greater than 35 the answer must be less than 3/4 or 75% of 50. Hence, (A) and (B) must be wrong.

Let's say all you can understand is greater or less than 10%. 10% of 50 is 5. 6 times 5 is 30. I.e. 30 is 60% of 50. Hence, (D) is wrong.

This leaves us with (C).