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Q:

# Three taps P, Q and R can fill a tank in 12 hrs, 15 hrs and 20 hrs respectively. If P is open all the time and Q and R are open for one hour each alternately, starting with Q, then the tank will be full in how many hours ?

 A) 9 hrs B) 7 hrs C) 13 hrs D) 11 hrs

Answer:   B) 7 hrs

Explanation:

Given,

P can fill in 12 hrs

Q can fill in 15 hrs

R can fill in 20 hrs

=> Volume of tank = LCM of 12, 15, 20 = 60 lit

=> P alone can fill the tank in 60/12 = 5 hrs

=> Q alone can fill the tank in 60/15 = 4 hrs

=> R alone can fill the tank in 60/20 = 3 hrs

Tank can be filled in the way that

(P+Q) + (P+R) + (P+Q) + (P+R) + ....

=> Tank filled in 2 hrs = (5+4) + (5+3) = 9 + 8 = 17 lit

=> In 6 hrs = 17 x 6/2 = 51 lit

=> In 7th hr = 51 + (5+4) = 51 + 9 = 60 lit

=> So, total tank will be filled in 7 hrs.

Q:

A contract is to be completed in 75 days and 187 men are to work 15 hours per day. After 65 days, 3/5 of the work is completed. How many additional men may be employed, so that the work may be completed in time, each man now working 17 hours per day?

 A) 532 B) 495 C) 308 D) 514

Answer & Explanation Answer: C) 308

Explanation:
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0 31
Q:

Pipes A, B and C together can fill a tank in 4 hours. Pipes A and B together can fill the tank in 9 hours. If pipes A, B and C are opened simultaneously, and after 3 hours, pipes A and B are closed, then how many hours will C alone require to fill the tank?

 A) 2.25 B) 2 C) 1.5 D) 1.8

Answer & Explanation Answer: D) 1.8

Explanation:
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0 33
Q:

If 18 men can cut a field in 35 days, then in how many days can 21 men cut the same field?

 A) 27 B) 28 C) 30 D) 32

Answer & Explanation Answer: C) 30

Explanation:
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0 41
Q:

A, B and C can individually complete a task in 24 days, 20 days and 18 days, respectively. B and C start the task, and they work for 6 days and leave. The number of days required by A alone to finish the remaining task, is:

 A) 1523days B) 1212days C) 845days D) 10 days

Answer & Explanation Answer: C) 845days

Explanation:
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0 83
Q:

Amit and Sunil together can complete a work in 9 days, Sunil and Dinesh together can complete the same work in 12 days, and Amit and Dinesh together can complete the same work in 18 days. In how many days will they complete the work if Amit, Sunil and Dinesh work together?

 A) 12 days B) 8 days C) 14 days D) 16 days

Answer & Explanation Answer: B) 8 days

Explanation:
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1 298
Q:

X can complete a work in 27 days and Y can do the same work in half of the time taken by X. Working together what part of the same work can they complete in a day?

 A) 1/9 B) 1/6 C) 1/12 D) 2/27

Answer & Explanation Answer: A) 1/9

Explanation:
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3 116
Q:

A, B and C can individually complete a task in 20 days, 16 days and 30 days, respectively. If A and B started working on the task, and they worked for 4 days and left, then the number of days required by C to finish the remaining task is:

 A) 16.5 days B) 13 days C) 10 days D) 12.5 days

Answer & Explanation Answer: A) 16.5 days

Explanation:
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4 181
Q:

A can do a piece of work in 6 days. B can do it in 9 days. With the assistance of C they completed the work in 3 days. In how many days can C alone do the work ?

 A) 18 B) 8 C) 12 D) 16

Answer & Explanation Answer: A) 18

Explanation:
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3 241