There are five same model cars parked in the same direction in parking. If 3 cars are red, 1 is black and 1 is green, in how many ways they can be arranged in the parking?
Options:
(A) 10 ways.
(B) 20 ways.
(C) 30 ways.
(D) 40 ways.
(E) 50 ways.

5!/(3!*1!*1!) = (5*4*3*2*1)/(3*2*1) = 120/6 = 20 ways. So the answer is: (B).

Two pipes A and B can fill a cistern in 20 and 30 minutes respectively, and a third pipe C can empty it in 40 minutes. How long will it take to fill the cistern if all the three are opened at the same time?
Options:
(A) 17 1/9
(B) 17 1/0
(C) 17 1/7
(D) 17 1/2
(E) 17 1/3

1/20 + 1/30 - 1/40 = 7/120
120/7 = 17 1/7 So the answer is: (C).

The edge of a cube is 3a cm. Find its surface?
Options:
(A) 64a2 cm2
(B) 54a2 cm2
(C) 84a2 cm2
(D) 24a2 cm2
(E) 34a2 cm2

6a2 = 6 * 3a * 3a = 54a2 So the answer is: (B).

Of the families in City X in 1994, 40 percent owned a personal computer. The number of families in City X owning a computer in 1998 was 30 percent greater than it was in 1994, and the total number of families in City X was 4 percent greater in 1998 than it was in 1994. what percent of the families in City X owned a personal computer in 1998?
Options:
(A) 50%
(B) 52%
(C) 56%
(D) 70%
(E) 74%
Say a 100 families existed in 1994 then the number of families owning a computer in 1994 - 40
Number of families owning computer in 1998 = 40 * 130/100 = 52
Number of families in 1998 = 104
The percentage = 52/104 * 100 = 50%. So the answer is: (A).