Answer:
Average rate at which the water level changed every week = -1.375 inches
Step-by-step explanation:
The water level of a lake fell by -11/2 inches during a 12/3 week-long dry spell.
Total fall of water level = -11/2 inches = -5.5 inches
Time of fall = 12/3 week = 4 weeks
[tex]\texttt{Average rate at which the water level changed every week}=\frac{\texttt{Total fall of water level}}{\texttt{Time of fall}}\\\\\texttt{Average rate at which the water level changed every week}=\frac{-5.5}{4}\\\\\texttt{Average rate at which the water level changed every week}=-1.375\texttt{inch per week}[/tex]
Average rate at which the water level changed every week = -1.375 inches
