q: A pipe can fill a cistern in 18 minutes whereas the cistern when fill can be emptied by a leak in 20 minutes. When both pipes are opened, find when the cistern will be full?
Options:
(A) 17
(B) 180
(C) 70
(D) 120
(E) 12
a: 1/18 - 1/20 = 1/180
180 minutes The answer is (B).
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q: A can do a piece of work in 4 hours; B and C together can do it in 3 hours, which A and C together can do it in 2 hours. How long will B alone take to do it?
Options:
(A) 1/19
(B) 1/11
(C) 1/12
(D) 1/17
(E) 1/14
a: A's 1 hour work = 1/4;
(B + C)'s 1 hour work = 1/3;
(A + C)'s 1 hour work = 1/2
(A + B + C)'s 1 hour work = (1/4 + 1/3) = 7/12
B's 1 hour work = (7/12 + 1/2) = 1/12
B alone will take 12 hours to do the work. The answer is (C).
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q: Every year an amount increases by 1/6th of itself. How much will it be after two years if its present value is Rs.64000?
Options:
(A) 87111
(B) 81007
(C) 81008
(D) 81066
(E) 81022
a: 64000* 7/6 * 7/6 = 87111 The answer is (A).
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q: Find the smallest number which should be multiplied with 560 to make it a perfect square.
Options:
(A) 60
(B) 55
(C) 45
(D) 25
(E) 35
a:
560 = 2*2*2*2*7*5
Required smallest number = 7 * 5 = 35
35 is the smallest number which should be multiplied with 560 to make it a perfect squar The answer is (E).
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