Without any water being pumped into the reservoir, or pumped out, a consistent rainfall could fill the reservoir in 24 days. If full the reservoir could drain itself (due to evaporation, etc) in 13 days.
a. The time it takes for the rain to fill the reservoir is 24 days. Express this as a rate. At what rate does the rain fill the reservoir (as in reservoirs per day)?
b. The time it takes for evaporation to drain the reservoir is 13 days. Express this as a rate. At what rate does evaporation drain the reservoir (as in reservoirs per day)?
c. Why under these conditions could the reservoir never fill up?