Question: The average mark obtained by 22 candidates in an examination is 45. The average of the first ten is 55 while the last eleven is 40 .The marks obtained by the 11th candidate is ?
Options:
(A) 2
(B) 0
(C) 9
(D) 8
(E) 6
Answer: It is clear that 22 x 45 = 10 x 55 + K + 11 x 40 K = 0
The answer is (B).

Question: The average age of 8 men increases by 2 years when two women are included in place of two men of ages 20 and 24 years. Find the average age of the women?
Options:
(A) 5
(B) 10
(C) 50
(D) 40
(E) 30
Answer: 20 + 24 + 8 * 2 = 60/2 = 30
The answer is (E).

Question: Twenty five percent of Country Y's yearly exports come from fruit exports. One-fifth of all fruit exports from Country Y are orange exports. If country Y generates $10 million from its orange exports, how much money does it generate from its yearly total of exports?
Options:
(A) $2125m
(B) $25m
(C) $200m
(D) $300m
(E) $153m
Answer: 25/100*1/5*(total) = 10
1/20*(total) = 10
(total) = 10*20 = 200
The answer is (C).

Question: P and Q can complete a work in 20 days and 12 days respectively. P alone started the work and Q joined him after 4 days till the completion of the work. How long did the work last?
Options:
(A) 5 days
(B) 9 days
(C) 30 days
(D) 20 days
(E) 10 days
Answer:
Work done by P in 1 day = 1/20
Work done by Q in 1 day = 1/12
Work done by P in 4 days = 4 (1/20) = 1/5
Remaining work = 1 1/5 = 4/5
Work done by P and Q in 1 day = 1/20 + 1/12 = 8/60 = 2/15
Number of days P and Q take to complete the remaining work = (4/5) / (2/15) = 6
Total days = 4 + 6 = 10
The answer is (E).