Water demand A reservoir supplies water to a community. During the summer months, the dema...

Water demand A reservoir supplies water to a community. During the summer months, the demand D(t) for water (in ft3/day) is given by

where t is time in days and t = 0 corresponds to the beginning of summer.

(a) Sketch the graph of D for 0 ≤ t ≤ 90.

(b) When is the demand for water the greatest?