How many words are memorized in the first 15 minutes?

Question

Suppose that in a memory experiment the rate of memorizing is given by M'(t)=−0.004t²+0.9t, where M'(t) is the memory rate, in words per minute.

Answer 1

M'(t) = −0.004t² + 0.9t

M(t) = (-0.004t³⁾/3 + (0.9t²)/2

Then M(15) = 96 words