q: If 85 percent of the test takers taking an old paper and pencil GMAT exam answered the first question on a given math section correctly, and 75 percent of the test takers answered the second question correctly, and 15 percent of the test takers answered neither question correctly, what percent answered both correctly?
Options:
(A) 60 %
(B) 65 %
(C) 70%
(D) 75%
(E) 80%
a: OK... {Total} = {First correctly} + {Second correctly} - {Both correctly} + {Neither correctly}
100 = 85 + 75 - {Both correctly} + 15
{Both correctly} = 75.
The answer is (D).

q: A car traveled from San Diego to San Francisco at an average speed of 63 miles per hour. If the journey back took twice as long, what was the average speed of the trip?
Options:
(A) 24.
(B) 32.
(C) 36.
(D) 42.
(E) 44.
a: OK... Let the time taken be = x
One way distance = 63x
Total distance traveled = 2 * 63x = 126x
Total time taken = x + 2x = 3x
Average speed = 126x/3x = 42
The answer is (D).

q: How many numbers can be made with digits 0, 7, 8 which are greater than 0 and less than a million?
Options:
(A) 496
(B) 486
(C) 1084
(D) 728
(E) 628
a:
OK... The number of single digit numbers = 2
The number of 2 digit numbers = 2 3 = 6
The number of 3 digit numbers = 2 3 3 = 18
The number of 4 digit numbers = 2 3 3 3 = 54
The number of 5 digit numbers = 2 3 3 3 3 = 162
The number of 6 digit numbers = 2 3 3 3 3 3 = 486
Therefore, the total numbers = 728
The answer is (D).