question: If 40 per cent of a number is added to an other number then it becomes 125 per cent of itself. What will be the ratio of first and second numbers?
Options:
(A) 8 : 5
(B) 5 : 7
(C) 5 : 8
(D) Data inadequate
(E) None of these
answer: Stream of consciousness: 40x100 + y = 125x100 xy = 2017 The answer is (E).
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question: The average of 11 results is 50, if the average of first six results is 49 and that of the last six is 52. Find the sixth result?
Options:
(A) 46
(B) 56
(C) 66
(D) 76
(E) 74
answer: Stream of consciousness: 1 to 11 = 11 * 50 = 550
1 to 6 = 6 * 49 = 294
6 to 11 = 6 * 52 = 312
6th = 294 + 312 550 = 56 The answer is (B).
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question: 10 books are placed at random in a shelf. The probability that a pair of books will always be together is
Options:
(A) 1/10
(B) 9/10
(C) 1/5
(D) 3/10
(E) 1/2
answer: 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).
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question: The average of first 12 even numbers is?
Options:
(A) 10
(B) 11
(C) 12
(D) 13
(E) 14
answer:
Stream of consciousness: Sum of 12 even numbers = 12 * 13 = 156
Average = 156/13 = 13 The answer is (D).
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