Rationale: Work done by the waste pipe in 1 minute = 1/15 - (1/20 + 1/24) = - 1/40
Volume of 1/40 part = 3 gallonsVolume of whole = 3 * 40 = 120 gallons.
The answer: (C)
Question: Two pipes can fill a tank in 20 and 24 minutes respectively and a waste pipe can empty 3 gallons per minute. All the three pipes working together can fill the tank in 15 minutes. The capacity of the tank is?
Options:
(A) 820 gallons
(B) 128 gallons
(C) 120 gallons
(D) 129 gallons
(E) 220 gallons
Reasoning: 7/8 * 6/7 = 3/4
1-(3/4) = 1/4
Ans: (B)
Question: A shipment of 8 TV sets contains 1 black and white sets and 7 color sets. If 2 TV sets are to be chosen at random from this shipment, what is the probability that at least 1 of the 2 sets chosen will be a black and white set?
Options:
(A) 1/7
(B) 1/4
(C) 5/14
(D) 11/28
(E) 13/28
Rationale: 1/18 - 1/36 = 1/36
36 minutes
The answer: (B)
Question: A pipe can fill a cistern in 18 minutes whereas the cistern when fill can be emptied by a leak in 36 minutes. When both pipes are opened, find when the cistern will be full?
Options:
(A) 17
(B) 36
(C) 70
(D) 13
(E) 12
Reasoning: A's 1 hour work = 1/3;
(B + C)'s 1 hour work = 1/2;
(A + C)'s 1 hour work = 1/2
(A + B + C)'s 1 hour work = (1/3 + 1/2) = 5/6
B's 1 hour work = (5/6 - 1/2) = 1/3
B alone will take 3 hours to do the work.
Ans: (B)
Question: A can do a piece of work in 3 hours; B and C together can do it in 2 hours, which A and C together can do it in 2 hours. How long will B alone take to do it?
Options:
(A) 6hours
(B) 3hours
(C) 2hours
(D) 5hours
(E) 4hours
Rationale: (1056 / 27) gives remainder 3
24 + 3 = 27, So we need to add 24
The answer: (D)
Question: What is the least number should be added to 1056, so the sum of the number is completely divisible by 27?
Options:
(A) 21
(B) 22
(C) 23
(D) 24
(E) 25
Rationale: 1/5:1/5:1/10 = 2:2:1
1/5*5000 = 1000
2000-1000 = 1000
The answer: (A)
Question: Rs. 5000 is divided into three parts A, B and C. How much A is more than C if their ratio is 1/5:1/5:1/10?
Options:
(A) 1000
(B) 992
(C) 772
(D) 552
(E) 312