A man rows his boat 90 km downstream and 45 km upstream, taking 2 1/2 hours each time. Find the speed of the stream?
Options:
(A) 9 kmph
(B) 6 kmph
(C) 5 kmph
(D) 8 kmph
(E) 7 kmph

Speed downstream = d/t = 90/(2 1/2) = 36 kmph
Speed upstream = d/t = 45/(2 1/2) = 18 kmph
The speed of the stream = (36 - 18)/2 = 9 kmph So the answer is: (A).

Four of the five parts numbered as (a), (b), (c), (d) and (e)in the following equations are exactly equal. You have to find out the part that is not equal to the other parts. The number of that part is the answer.
Options:
(A) a2 + 5ab + 6b2
(B) (a + 3b) (a + 2b)
(C) a(a + 3b) + 2b(a + 3b)
(D) (3a + b) (a + 2b)
(E) a(a + 2b) + 3b(a + 2b)

The other parts are equal to a2 + 5ab + 6b2. So the answer is: (D).

A man rows his boat 72 km downstream and 30 km upstream, taking 3 hours each time. Find the speed of the stream?
Options:
(A) 6 kmph
(B) 5 kmph
(C) 2 kmph
(D) 8 kmph
(E) 7 kmph

Speed downstream = d/t = 72/(3) = 24 kmph
Speed upstream = d/t = 30/(3) = 10 kmph
The speed of the stream = (24 - 10)/2 = 7 kmph So the answer is: (E).

Suzy has a lot of skeins of yarn, she has blue, yellow, and red yarn. She has twice as much blue yarn as yellow yarn, and she has twice as much yellow yarn as she has red yarn. If she has X skeins of yarn, how many of the skeins are red, in terms of X?
Options:
(A) X/8
(B) X/7
(C) X/6
(D) X/5
(E) X/4
Since the total number of skeins is X, then X = Blue + Yellow + Red
Because there are twice as many Blue as Yellow, then Blue = 2*Yellow
Thus X = 2*Yellow + Yellow + Red, which simplifies to X = 3*Yellow + Red
Because there are twice as many Yellow as Red, then Yellow = 2*Red
Thus X = 3*(2*Red) + Red, which simplifies to X = 7*Red
Therefore Red = X/7 So the answer is: (B).