51.

Water flows into a reservoir which is 200 m long and 150 m wide, through a pipe of cross-section (0.3m X 0.2m) at 20kmph. In what time will the water level be 8?

 A. 100 hrs B. 150 hrs C. 175 hrs D. 200 hrs
Answer:D
Explanation: Volume of water collected in the tank in 1 hour ⇒ 0.3×0.2×20×1000=1200 m cubic If after t hours, the water is at height of 8m, 1200t=200×150×8 ⇒ t = 200 Hours.

52.

A work is done by three person A,B and C. A alone takes 10 hours to complete a single product but B and C working together takes 4 hours, for the completion of the same product. If all of them worked together and completed 14 products, then how many hours have they worked?

 A. 20 hrs B. 28 hrs C. 40 hrs D. 54 hrs
Answer:C
Explanation: 1 A =10 and 1 B + 1 C = 1 4 (Given) 1 A + 1 B + 1 C = 1 4 + 1 10 = 7 20 In 20 hours, working together they will complete 7 products. Thus in 40 hours they will complete 14 products

53.

Four men and three women can do a job in 6 days. When five men and six women work on the same job, the work gets completed in 4 days. How many days will a woman take to do the job, if she works alone on it.

 A. 18 B. 36 C. 54 D. None of these
Answer:C
Explanation: Let the amount of work done by a man in a day be ‘m’ and the amount of work done by a woman in a day be ‘w’. Therefore, 4 men and 3 women will do 4m+3w amount of work in a day. If 4 men and 3 women complete the entire work in 6 days, they will complete ( 1 6 )th of the work in a day. Hence, 4m+3w= 1 6 --------------- (1) and from statement (2), 5m+6w= 1 4 ----------------- (2) Solving eqn (1) and eqn (2), we get 3m= 1 12 or m= 1 36 . i.e. a man does ( 1 36 )th of the work in a day. Hence he will take 36 days to do the work. Substituting the value of m in eqn (1), we get 4× 1 36 +3w= 1 6 ⇒ 3w= 1 6 − 1 9 =3− 2 18 = 1 18 or w= 1 54 . i.e. a woman does ( 1 54 )th of the work in a day. Hence she will take 54 days to do the entire work.

54.

A pump can be used either to fill or to empty a tank. The capacity of the tank is 3600m3. The emptying capacity of the pump is 10m3/min higher than its filling capacity. What is the emptying capacity of the pump if the pump needs 12 more minutes to fill the tank than to empty it?

 A. 10 m3 min B. 60 m3 min C. 45 m3 min D. 90 m3 min
Answer:B
Explanation: Let 'f' m3/min be the filling capacity of the pump. Therefore, the emptying capacity of the pump will be =(f+10)m3/min. The time taken to fill the tank will be= 3600 f minutes And the time taken to empty the tank will be = 3600 f+10 . We know that it takes 12 more minutes to fill the tank than to empty it i.e 3600 f – 3600 f+10 =12 ⇒ 3600f+36000−3600f=12(f2+10f) ⇒ 36000=12(f2+10f) ⇒ 3000=f2+10f ⇒ f2+10f−3000=0. Solving for positive value of 'f' we get, f=50. Therefore, the emptying capacity of the pump =50+10= 60 m3/min

55.

Working together, A and B can do a job in 6 days. B and C can do the same job in 10 days, while C and A can do it in 7.5 days.

 A. 8 B. 5 C. 3 D. 7
Answer:B
Explanation: Even before you start working on the problem, check out if you can eliminate some answer choices as impossible. We know that if A and B alone work, they can complete the job in 6 days. Therefore, if all three of them A, B and C work together the number of days it will take to complete the job will surely be less than 6 days. Hence, we can eliminate answer choices (1) and (4) right away. Let A be the number of days that A will take to complete the job alone, B days for B to complete the job alone and C days for C to complete the job alone. A and B can do a job in 6 days. They complete ( 1 6 )th of the job in a day. i.e. 1 A + 1 B = 1 6 ------- -- (1) Similarly, B and C will complete ( 1 10 )th of the job in a day. i.e 1 B + 1 C = 1 10 ---------- (2) And C and A will complete 1 7.5 or ( 2 15 )th of the job in a day i.e 1 C + 1 A = 2 15 ------------ (3). Adding (1), (2) and (3) we get: 1 A + 1 B + 1 B + 1 C + 1 C + 1 A = 1 6 + 1 10 + 2 15 ⇒ 2 A + 2 B + 2 C = 5+3+4 30 ⇒ 1 A + 1 B + 1 C = 6 30 = 1 5 . i.e working together, A, B and C complete ( 1 5 )th of the job in a day. Therefore, they will complete the job in 5 days.