Answer :
Given that,
The water level of a lake rose by 1 2/3 in. during a 3 1/3 week-long wet spell. We need to find the average rate at which the water level changed every week. It is a problem based on the concept of ratio. So,
[tex]R=\dfrac{1\dfrac{2}{3}}{3\dfrac{1}{3}}\\\\=\dfrac{\dfrac{5}{3}}{\dfrac{10}{3}}\\\\=\dfrac{5}{3}\times \dfrac{3}{10}\\\\=\dfrac{1}{2}[/tex]
So, the average rate at which the water level changed every week is 1/2 inches/week.