Question

Growth and Decay :) i only need help with the part (c)

Under certain climatic conditions the number N of blue-green algae satisfied the equation:
N(t) = Ae^(0.15t)
where t is measured in days and A is a constant.

(a) Show that the number of algae increases at a rate proportional to the number present.
(b) When t=3 the number of algae was estimated to be 1.7 x 10^8. Evaluate A.
(c) The number of algae doubles every n days. Find n.

Answer 1

but the real problem is Part (c) .