OA: E
My Answer: C
My Explanation:
Say, total gallons of water in tank X = a
Total gallons of water in tank Y = b
Rate of draining of water from tank X = r1
Rate of draining of water from tank Y = r2
Time taken of draining water from both tanks is same hence
a/r1 = b/r2
Also, a = b + 30
We have to find the time to drain i.e either value of a/r1 or b/r2
1) r1 = 2 * r2
So the equation becomes,
(b+30)/2 * r2 = b/r2
We can solve it to find that, a = 45 and b = 15.
But we don’t know r1 or r2 hence INSUFFICIENT
2) r2 = 20 gallons/hr
So the equation becomes,
(b+30)/r1 = b/20
INSUFFICIENT
Together, we know b = 15 and r2 = 20 hence time will be 15/20 hrs. Hence (C)
