Inspired wrote:Two water tanks, X and Y, were drained simultaneously. If X contained 30 more gallons of water than Y, and both tanks became empty at the same time, how long did it take the tanks to empty?
(1) For every gallon drained from tank Y, 2 gallons were drained from tank X.
(2)Tank Y was drained at a constant rate of 20 gallons per hour.
pls ans
Say tank X contained x gallons of water and Tank Y contained y gallons of water
Now the question says x = y+30
The rate of drainage for Tank X is say a and rate of Drainage for tank Y is say b
now the time taken for draining X = Time Taken for draining Y
=> x/a = y/b
=> y+30/a = y/b
Now we want the time required to drain the tanks
that is x/a or y/b
Now let us look at the options
option 1 says a = 2b
=> y+30/2b = y/b
y+30 = 2y
y =30
but we want y/b
so 1 alone is not sufficient
Option 2 says
b= 20 gallons per hour
which alone is not sufficient
but if we combine 1&2
Time taken to drain the tank y/b = 30/20 = 1.5 hours
thus the question can be solved combining 1&2
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