Question: If six persons sit in a row, then the probability that three particular persons are always together is?
Options:
(A) 1/9
(B) 1/6
(C) 1/5
(D) 1/2
(E) 1/3
Ans: (C)
CoT: Six persons can be arranged in a row in 6! ways. Treat the three persons to sit together as one unit then there four persons and they can be arranged in 4! ways. Again three persons can be arranged among them selves in 3! ways. Favourable outcomes = 3!4! Required probability = 3!4!/6! = 1/5
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Question: A 70 cm long wire is to be cut into two pieces so that one piece will be 2/5th of the other, how many centimeters will the shorter piece be?
Options:
(A) 20
(B) 40
(C) 45
(D) 25
(E) 60
Ans: (A)
CoT: 1: 2/5 = 5: 2
2/7 * 70 = 20
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Question: A man sells two articles for Rs.3600 each and he gains 30% on the first and loses 30% on the next. Find his total gain or loss?
Options:
(A) 9 % loss
(B) 10% gain
(C) 450
(D) 12% loss
(E) 12% gain
Ans: (A)
CoT: (30*30)/100 = 9%loss
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