A cistern has a leak which would empty it in 8 hours. A tap is turned on which admits 6 litres a min

M4maths Previous Puzzles

21 Oct 2015 Time and work

A cistern has a leak which would empty it in 8 hours. A tap is turned on which admits 6 litres a minute into the cistern and it is now emptied in 12 hours. How many litres does the cistern hold?

OPtion

1) 7580
2) 7650
3) 7780
4) 7960
5) 8080
6) 8290
7) 8640
8) 7260
9) 7450
10)None of these

Solution

Part filled in 1 hours = (1/8 - 1/12) = 1/24
Therefore Time taken to fill the cistern = 24 hours
Water moved in 24 hours = (6*24*60) litres = 8640 litres
Option 7)

Correct Option: 7 Best Solution (5)

Aditya Narayan Singh   9 years AGO

lets take 24 work that is lcm of 8 hours and 12 hours.

then 24 work completed by 8 hours pipe that is 3 work per hour for empatied

then 24 work completed by 12 hours pipe that is 2 work per hour for fill the tank

diffrence of both that is 1 work per hour

then 24/ 1 ie 24 hour to take to empty the tank

hence tank capacity = 6 * 60 * 24 = 8640.

Like? Yes (32) | No (5)  

Abhisheak Kumar Missu   9 years AGO

time taken to fill the tank=1/8-1/12=1/24
since capacity of tank=24*60*6=8640

Like? Yes (12) | No (2)  

RAHUL KUMAR   9 years AGO

Part filled in 1 hour = 1/8-1/12
=1/24
Time taken to fill the cistern =
24 hrs.
Water moved in it in 24 hrs =
(6 x 60 x 24) litres = 8640
litres
Capacity of the cistern = 8640
litres.

Like? Yes (16) | No (6)  

ABHINAV PUSHPAM   9 years AGO

1/8-1/12= 1/24
So capacity will be 24*360= 8640
Option 7)

Like? Yes (6) | No (5)  

MRITUNJAY   9 years AGO

B A A-B

-8 6lit/min -12
24
-3. 1 -2
so A takes 24 hours to fill.

capacity of tank is 6*60*24=8640 litre

Like? Yes (3) | No (5)