Barrons AP Calculus

Since   Q(1)    =   0.8Q 0 ,    0.8Q 0  =   Q 0 ek·1,   0.8 =   ek, and

Q(t)    =   Q 0 (0.8)t.

We  seek    t   when    Q(t)    =   0.02Q 0 .   Thus,

0.02Q 0     =   Q 0 (0.8)t

and

t   17.53   min.

Section II Free-Response