Answer: 645 letters per hour
Step-by-step explanation:
Given : After t months on the job, a postal clerk can sort [tex]Q(t)=700-410 e^{-0.5t}[/tex] letters per hour.
Then the average rate at which he clerk sorts mail during the first 4 months on the job, we put t= 4 , we get
[tex]Q(t)=700-410 e^{-0.5\times4}\\\\\Rightarrow] Q(t)=700-410e^{-2}\\\\\Rightharrow700-55.487466127=644.512533873\approx645[/tex]
Hence, the average rate at which he clerk sorts mail during the first 4 months on the job = 645 letters per hour
