GMAT Question of the Day (Feb 16): Word Problem (Rate) and Sentence Correction

Math (PS)

Water flows into an empty tank of 54 liters via 12 small pipes. The rate of each pipe is 1 liter per hour. However, water flows out of the tank via several big pipes at the rate of 1.5 liter per hour. If after 12 hours, the tank is completely full, how many big pipes are there?

(A) 2.5
(B) 3
(C) 4
(D) 5
(E) 6

OA and Explanation

Verbal (SC)

In the 1980’s the rate of increase of the minority population of the United States was nearly twice as fast as the 1970’s.

(A) twice as fast as
(B) twice as fast as it was in
(C) twice what it was in
(D) two times faster than that of
(E) two times greater than

OA and Explanation

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