FRQ ore processing

Question

On a given workday, the rate, in tons per hour, at which unprocessed ore arrives at a refinery is modeled by O (t) = 20 + 10cos(t²/25), where t is measured in hours and 0 (less than or equal to) t (less than or equal to) 10.

Determine the time at which the total rate of ore at the refinery is neither increasing nor decreasing.

Answer 1

dO/dt=-10sin(t^2/25) *2t/25=0

t=0 or sin(t^2/25)=0

t^2/25=n*pi, n=0,1,2,3..

t=5(n*pi)**0.5, n=0,1,2,3,4...

0<=t<=10, n=0,1 are thus the only answers.