q: A pharmaceutical company received $5 million in royalties on the first $40 million in sales of and then $9 million in royalties on the next $210million in sales. By approximately what percentage did the ratio of royalties to sales decrease from the first $40 million in sales to the next $210 million in sales?
Options:
(A) 8%
(B) 15%
(C) 45%
(D) 52%
(E) 66%
a: OK... (9/210)/(5/40) = 12/35 = 34% it means that 9/210 represents only 34%. Therefore a decrease of 66%.
The answer is (E).

q: A pipe can fill a cistern in 20 minutes whereas the cistern when fill can be emptied by a leak in 28 minutes. When both pipes are opened, find when the cistern will be full?
Options:
(A) 76 minutes
(B) 29 minutes
(C) 70 minutes
(D) 17 minutes
(E) 98 minutes
a: OK... 1/20 - 1/28 = 1/70
70 minutes
The answer is (C).

q: Which of the following is equal to the average (arithmetic mean) of (x+5)^2 and (x-5)^2?
Options:
(A) x^2
(B) x^2+2
(C) x^2 +30
(D) x^2+20
(E) x^2+25
a:
OK... Avg = [(x+5)^2 + (x-5)^2] / 2
Expanding and simplifying, (x^2 + 10x + 25 + x^2 - 10x + 25) / 2 = x^2 + 25
The answer is (E).