Assume That the Profit P Made When T $t > 0$

Multiple Choice

Assume that the profit P made when t units are sold, $t > 0$ , is given by $P ( t ) = t ^ { 2 } - 18 t + 72$ For what values of t will there be a profit (that is, $\mathrm { P } > 0 )$ ?

A) t=18
B) $6 < t < 12$
C) t=6 or t=12
D) $0 < t < 6 \text { or } t > 12$