q: 10 books are placed at random in a shelf. The probability that a pair of books will always be together is ?
Options:
(A) 1/8
(B) 1/2
(C) 1/5
(D) 1/5
(E) 1/3
a: Stream of consciousness: 10 books can be rearranged in 10! ways consider the two books taken as a pair then number of favourable ways of getting these two books together is 9! 2!
Required probability = 1/5 The answer is (C).


question: The average of first six prime numbers greater than 20 is?
Options:
(A) 10
(B) 20
(C) 30
(D) 40
(E) 34
answer: Stream of consciousness: 23 + 29 + 31 + 37 + 41 + 43 = 204/6 = 34 The answer is (E).


q: A farm used two harvesting machines, H and K, to harvest 100 acres of wheat. Harvesting machine H, working alone at its constant rate, harvested 30 acres of wheat in 8 hours. Then harvesting machine K was brought in, and harvesting machines H and K, working together at their respective constant rates, harvested the remaining acres of wheat in 7 hours. Harvesting machine K harvested how many acres of wheat per hour?
Options:
(A)  7
(B)  8
(C)  12
(D)  3
(E)  15
a: Stream of consciousness: Rate of H = 7 acres/hr
Remaining land to be harvested = 100 - 30 = 70
Rate of H and K = 70/7 = 10 acres/hr
Rate of K = 10 - 7 = 3 The answer is (D).


question: How long does a train 110 m long traveling at 72 kmph takes to cross a bridge of 170 m in length?
Options:
(A) 16.5
(B) 16.0
(C) 16.4
(D) 14
(E) 16.1
answer: Stream of consciousness: D = 110 + 170 = 280 m
S = 72 * 5/18 = 20
T = 280 * 1/20 = 14 sec The answer is (D).


q: What is the area of a square with perimeter 16P ?
Options:
(A)  16p^2
(B)  4P
(C)  P^2/4
(D)  P/16
(E)  P^2/16
a: Stream of consciousness: Each side is 4p
A = (4p)^2 = 16(p^2) The answer is (A).


q: If the cost price of 50 articles is equal to the selling price of 15 articles, then the gain or loss percent is?
Options:
(A) 16
(B) 127
(C) 12
(D) 18
(E) 233
a:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
Stream of consciousness: Percentage of profit = 35/15 * 100 = 233% The answer is (E).