Given that one inlet pipe can fill an empty pool in 4 hours. The outlet pipe can empty the pool in 8 hours. We know that rate x time = work done.
Rate = work done / time
Rate of inlet pipe = ¼ hours.
Rate of outlet pipe = 1/8 hours
Here 1 represent the work completed.
Let x be the time taken to fill the pool by the inlet pipe if the drain is left.
Work done by inlet pipe – work done by outlet pipe = 1 work completed.
x/4 – x/8 = 1.
To solve the rational equation, first we clear the fractions by multiplying it with LCD (4,8)=8 to each item.
8(x/4) – 8(x/8) = 8(1)
2x – x = 8
X = 8
Time taken for the pipe to fill the pool if the drain is left open = 8 hours