4. A draining pipe can empty a pool in 4 hours. On a rainy day, when the pool is full, the draining pipe is opened and the pool is emptied in 6 hours. If rain inflow into the pool is 3 liters per hour, what is the capacity of the pool?
A. 9 liters
B. 18 liters
C. 27 liters
D. 36 liters
E. 45 liters
My thought process was quite dumb so putting it here incase any one else is thinking in the same direction:
I was misguided by the mention of 3 ltrs per hour and I ended up thinking additional water in the pool was emptied in the extra 2 hours (additional water due to rain was 3 ltr * 2 hrs=6 ltrs)
It rained for 6 hours in fact and additional water in the pool was 3 ltrs * 6 hours =18 ltrs
In each additional hour 9 ltr water was emptied. 9 ltr/ hour
So, in 4 hours (without rain) emptied water (capacity of the pool) is 9 ltr * 4 hours= 36 ltrs (D)