Question: Before lunch, a painter can paint a wall at a rate of r square feet per minute. The same painter, after lunch and a cup of coffee, can paint the same wall at a rate r + 1 square feet per minute, and the same wall would be finished in 30 seconds less time. What is the value of r?
Options:
(A) 1/3
(B) 3
(C) 1/2
(D) 1
(E) 2
Answer: Convert 30 seconds to 1/2 minute
Equation: 1/r = 1/(r + 1) + 1/2
Plug options into the equation:
D fits: 1/1 = 1/(1 + 1) + 1/2
The answer is (D).

Question: When N is divided by 10 the remainder is 1 and when N is divided by 3 the remainder is 2. What is the remainder S when N is divided by 30?
Options:
(A) (a) 4
(B) (b) 7
(C) (c) 11
(D) (d) 13
(E) (e) 17
Answer: N ends in the digit 1 because when N is divided by 10, the remainder is 1. Since N ends in 1, the remainder S when N is divided by 30 also ends in a 1. 11 is the only choice which ends in a 1.
The answer is (C).

Question: How many terminating zeroes R does 200! have?
Options:
(A) 40
(B) 48
(C) 49
(D) 55
(E) 64
Answer: You have 40 multiples of 5, 8 of 25 and 1 of 125. This will give 49 zeros.
The answer is (C).

Question: 49 members attended the party. In that 22 are males, 27 are females. The shake hands are done between males, females, male and female. Total 12 people given shake hands. How many such kinds of such shake hands are possible?
Options:
(A) 66
(B) 291
(C) 26
(D) 29
(E) 11
Answer:
If only 12 people shaked their hands, then total hand shakes are 12C212C2 = 66
The answer is (A).