I have this question but I'm not really sure what the answer is. It says for $1$ week so does it mean the interval is $0 \leq x\leq7$? When I drew the graph $7$ had the lowest $y$ value, does it mean it is the warmest at $7$? I was wondering if you could help me out.
Question: the thickness of the ice on a lake for one week is modeled by the function: $$T(d)=-0.1d^3+1.2d^2-4.4d+14.8$$ where $T$ is the thickness in cm and $d$ is the number of days after December $31$st. a) when does the warmest day occur during this week? determine the average rate of change in a short interval near the point you chose.