ANSWERS - HURDLE 09 : CISTERN

Ans1(a) : 1/20 + 1/10 –1/24 – 1/120 = 1/10
In 4 hours fill 1/10.
In 36 hours will fill = 9/10
In next 1 hour will fill 1/20 (37 Hours) = 9/10 +1/20 = 95/100
In next 1/2 hour will fill 1/20 (37.5 hours) = 95/100 +1/20 = 1.00
So it will be full in 37.5 hours.

Ans 1(b) : 1/10 –1/24 –1/120 = 1/20
In fourth hour there is no action , so in every 4 hours the tank will be 1/20th full. (UrPercentile.com)
In 76 hours the tank will be 19/20 full
In next 1/2 hour the tank will be 1/20 full as pipe B will be activated.
19/20 +1/20 = 1
So the tank will be full in 76.5 hours.

Ans2. First two inlet pipes each can fill 1/50 th of the tank per hr : total 2/50th = 1/25 th
b. Other two inlet pipes each can fill 1/200 th of the tank per hr : total 2/200th = 1/100 th
c. First two outlet pipes each can drain 1/100 th of the tank per hr : total 2/100th = 1/50 th
d. Each of the 5 leaks can drain 1/1000 th of the tank per hr : total 5/1000th = 1/200th
Per hour storage = fill - drain =1/25 + 1/100 -1/50 -1/200 =(8+2-4- 1)/200=5/200=1/40
Therefore, time needed to fill the tank = 40 hrs.


Ans 3. Total fill per hour = 1/25 + 1/100 = 1/20
The time needed to fill the tank = 20 hrs


Ans 4. From above two ans, the inlet pipes can fill the tank twice in 40 hrs. when there's no outflow, and once in 40 hrs when outlets are open.
Therefore, The outlets can drain the tank in 40 hrs when there is no inflow.

Ans 5. Let the capacity of tank be X lts. Two inlet pipes have capacity of 20 lts/ hours each and 3 inlet pipes have capacity of 40 lts/ hour each Total inlet capacity = 20*2+ 40*3=160 lts/hour
Similarly Total Outlet capacity of 10 pipes = 2*10+ 8*5= 60 lts/ hour.
If all inlet and outlet pipe work together total capacity becomes
160-60 =100 lts/hour. (UrPercentile.com)
It takes 80 hours to fill the tank so the capacity = 80*100=8,000 lts.

Ans 6. If only the inlet pipes are working it will take 8000/160= 50 hours to fill the tank.

Ans 7. It will take 8000/60= 133.33 hours to empty the tank

Ans 8. Volume becomes double so it become 16,000 Lts It would take 80 *2= 160 hours to fill the two tanks.

Ans 9~11

Tank Capacity = 6500
INLET CAPACITY The first and second pipe fill in 65 hours each
So the first and second pipe have capacity of (6500/65) 100 lts/
hours each
OUTLET CAPCITY : 50*2=100 lts/ hour + capacity of 5 leaks
Each leak empty in 1300 hours . So capacity of each leak = 6500/
1300 = 5 lts/ hours. (UrPercentile.com)
Total capacity of leaks = 5*5 =25 lts/hour
Total Outlet capacity =100+25=125 Lts/hours

Ans 9 : All working together fill the tank in 52 hours.
So the rate of filling = 125 lts/ hour
Let capacity of 3rd and 4th pipe be X lts/hour
so 2.100+ 2.X-125= 125
or 2X= 50
or X=25
So capacity of 3rd and 4th pipe is 25 lts/hour

Ans 10. Total inlet capacity = (2*100)+(2*25)=250
So if only the inlet pipe are working the tank will be full in 6500/
250= 26 hours.

Ans 11. 6500/125= 52 hours

Ans 12. 7200 Litres

Ans 13. 90 Hours

Ans 14. 180 Hours

Ans 15. 10 litres per hour for each of the six,

Ans 16. 30 litres per hour ,

Ans 17. 15 Hours ,

Ans 18. 12 Hours and 30 minutes ,

Ans 19. 30 Hours,

Ans 20. B, Ans 21. J, Ans 22. A, Ans 23. F, Ans 24. I, Ans 25. D,

Ans 26. Option 2 is the best.
Option 3 is not correct as the author did a good job in establishing link between two cultures. Read " Hubris would be a easonable accusation, were it not that he succeeds so well"
If the length of the novel was the reason it should have been mentioned at the end, moreover it says "it is as if five hundred
pages rather than two have passed"