q: At what rate percent on simple interest will a sum of money double itself in 30 years?
Options:
(A) 3 1/9%
(B) 3 7/3%
(C) 7 1/3%
(D) 5 1/3%
(E) 1 1/3%
a: OK... P = (P*30*R)/100
R = 3 1/3%
The answer is (A).

q: For a particular American football game, the probability of a team's quarterback throwing a completed pass on each throw is 3/10. What is the least number of times that the quarterback should throw the ball that will increase the probability of getting a completed pass at least once to more than 50%.
Options:
(A) 10
(B) 5
(C) 2
(D) 3
(E) 1
a: OK... Rule of Subtraction: P(A) = 1 - P(A')
Rule of Multiplication: P(A B) = P(A) P(B)
The probability that the quarterback throws a completed pass at least once in 2 throws is 1- (7/10)^2 = 1 - 49/100 = 51/100 > 50%
The answer is (C).

q: In a school of 850 boys, 44% of Muslims, 28% Hindus, 10% Sikhs and the remaining of other communities. How many belonged to the other communities?
Options:
(A) 277
(B) 267
(C) 153
(D) 188
(E) 151
a:
OK... 44 + 28 + 10 = 82%
100 82 = 18%
850 * 18/100 = 153
The answer is (C).