question: A and B can do a work in 12 days, B and C in 30 days and C and A in 36 days. In how many days will the work be completed, if all three of them work together?
Options:
(A) 180/15
(B) 180/10
(C) 180/13
(D) 180/15
(E) 180/11
answer: Stream of consciousness: One day work of A and B = 1/12
One day work of B and C = 1/30
One day work of C and A = 1/36
2(A + B + C) = 1/12 + 1/30 + 1/36
2(A + B + C) = 13/90
(A + B + C) = 13/180
Number of days required = 180/13 days. The answer is (C).
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question: A train running at the speed of 60 km/hr crosses a pole in 12 sec. What is the length of the train?
Options:
(A) 120 m
(B) 200 m
(C) 115 m
(D) 110 m
(E) 150 m
answer: Stream of consciousness: Speed = 60 * 5/18 = 50/3 m/sec
Length of the train = speed * time = 50/3 * 12 = 200 m The answer is (B).
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question: In a school of 850 boys, 44% of Muslims, 28% Hindus, 10% Sikhs and the remaining of other communities. How many belonged to the other communities?
Options:
(A) 277
(B) 267
(C) 153
(D) 188
(E) 151
answer: Stream of consciousness: 44 + 28 + 10 = 82%
100 82 = 18%
850 * 18/100 = 153 The answer is (C).
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question: Find the third proportional to 2 and 8?
Options:
(A) 10
(B) 32
(C) 36
(D) 19
(E) 20
answer:
Stream of consciousness: Formula = Third proportional = (b b)/a
A = 2 and B = 8
(8 x 8 )/ 2 = 64/2 = 32 The answer is (B).
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