Question 619·Easy·Math

Type $a=[81,80,81,81,82]$ in Desmos, then type $\operatorname{median}(a)$. Desmos prints $81$. The median is the middle value after sorting: $80,81,81,81,82$. Keep all three repeated readings in the list, so its third value is $81$ °F.

Add $\operatorname{mean}(a)$ in Desmos; it prints $81$. The mean is the total divided equally among the five days. The $80$ is $1$ below $81$, and the $82$ is $1$ above, so they balance each other while the other three readings equal $81$.

The mode is the value that occurs most often. $81$ occurs three times; $80$ and $82$ occur once each. So the mode is $81$ °F. Don't report the count of three as the mode; the mode is a temperature.

The range is the largest reading minus the smallest: $\max(a)-\min(a)$. Add that expression in Desmos; it prints $2$, using $82$ and $80$ as the endpoints. The range is a difference between readings, not a typical reading. So the range is $2$ °F, which is not $81$ °F. Choice D.