Question: The no. of girls in a class are seven times the no. of boys, which value can neverbe the of total students?
Options:
(A) 4
(B) 5
(C) 8
(D) 10
(E) 12
Ans: (C)
CoT: Let the boys are X, then girls are 7X, total = X+7X = 8X
So it should be multiple of 8, 30 is not a multiple of 8.
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Question: How long does a train 110 m long traveling at 60 kmph takes to cross a bridge of 390 m in length?
Options:
(A) 18.9 sec
(B) 88.9 sec
(C) 22.9 sec
(D) 30.00 sec
(E) 72.0 sec
Ans: (D)
CoT: D = 110 + 390 = 500 m
S = 60 * 5/18 = 50/3
T = 500 * 3/50 = 30 sec
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Question: Anil can do a work in 15 days while Sunil can do it in 25 days. How long will they take if both work together?
Options:
(A) 3 4/9 days
(B) 8 4/9 days
(C) 9 3/8 days
(D) 6 3/8 days
(E) none of these
Ans: (C)
CoT: 1/15 + 1/25 = 8/75
75/8 = 9 3/8 days
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