arjtryarjtry wrote:
With both valves open, the pool will be filled with water in 48 minutes. The first valve alone would fill the pool in 2 hours. If the second valve emits 50 cubic meters of water more than the first every minute, then what is the capacity of the pool?
A. 9000 cubic meters
B. 10500 cubic meters
C. 11750 cubic meters
D. 12000 cubic meters
E. 12500 cubic meters
M12-10
Hi,
I would think of this in TWO ways if I had to do this Qs WITHOUT getting into serious calculation..
1) USE of CHOICES, as also explained above-Very helpful in many calculations..
Ofcourse here, we believe that the speed, x here, must be integer..
so total = 48(x+x+50)..
so our answer should be a multiple of 48 or 3*16...C and E are not multiple of 3..
A and B are multiples of 3, but not of 16..
D
2) second method.. In 48 minutes, the faster valve fills up 48*50=2400 more than 1st...
If both took same time as first,that is same speed, the tank would have been filled in 1 hour..
so in 60 - 48= 12 minutes, both would have filled 2400 cum..
BUT first one alone will fill it up in 12*2 = 24 mins...
if the first fills up 2400 in 24 mins..
it will fill 100 in 1 min and 12000 in 120 mins or 2 hours..
so Capacity of tank = 12000cumD