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) 180/18
(B) 180/15
(C) 180/13
(D) 180/12
(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: Two trains are moving at 85 kmph and 70 kmph in opposite directions. Their lengths are 150 m and 100 m respectively. The time they will take to pass each other completely is?
Options:
(A) 5 25/31 sec
(B) 7 1/17 sec
(C) 7 2/2 sec
(D) 8 1/2 sec
(E) 7 1/9 sec
answer: Stream of consciousness: 70 + 85 = 155 * 5/18 = 775/18 mps
D = 150 + 100 = 250 m
T = 250 * 18/775 = 180/31 = 5 25/31 sec The answer is (A).
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question: A train does a journey without stoppage in 8 hours, if it had travelled 5 km/h faster, it would have done the journey in 6 hours 40 minutes. Find its original speed.
Options:
(A) 25 km/h
(B) 40 km/h
(C) 45 km/h
(D) 36.5 km/h
(E) None of these
answer: Stream of consciousness: Let original speed = S km/h
Here, distance to be covered is constant
S 8 = (S + 5)(203)
8S - 203S = 1003 S = 1004 = 25 km/h The answer is (A).
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question: Rs. 1300 is divided into three parts A, B and C. How much A is more than C if their ratio is 1/8:1/3:1/4?
Options:
(A) Rs.224
(B) Rs.216
(C) Rs.100
(D) Rs.300
(E) Rs.400
answer:
Stream of consciousness: 1/8:1/3:1/4 = 4:8:6
3/18*1300 = 216 The answer is (B).
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