Question: In what time will a railway train 40 m long moving at the rate of 36 kmph pass a telegraph post on its way?
Options:
(A) 3 sec
(B) 4 sec
(C) 5 sec
(D) 6 sec
(E) 7 sec
Ans: (B)
CoT: T = 40/36 * 18/5 = 4 sec
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Question: If A takes x days to do a work then B takes 2x days to do the same work then with in how many day's A will alone complete this work ?
Options:
(A) 27
(B) 23
(C) 24
(D) 25
(E) 26
Ans: (A)
CoT: 1/x+1/2x = 1/18 = > 3/2x = 1/18 = > x = 27 days. Hence, A alone can finish the work in 27 days.
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Question: The average of 13 numbers is 60. Average of the first 7 of them is 57 and that of the last 7 is 61. Find the 8th number?
Options:
(A) 46
(B) 82
(C) 45
(D) 43
(E) 53
Ans: (A)
CoT: Sum of all the 13 numbers = 13 * 60 = 780
Sum of the first 7 of them = 7 * 57 = 399
Sum of the last 7 of them = 7 * 61 = 427
So, the 8th number = 427 + 399 - 780 = 46.
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