A Bacterial Culture Grows According to the Formula $P = P _ { \mathrm { o } } a ^ { t }$

Multiple Choice

A bacterial culture grows according to the formula $P = P _ { \mathrm { o } } a ^ { t }$ . If it takes 8 days for the culture to triple in size, how long will it take to double in size?

A) $\quad 4.8$ days
B) $\quad - 1.1$ days
C) none of these
D) $\quad 1.9$ days
E) $\quad 0.2$ days