A regression was run to determine if there is a relationship between hours of TV watched per day $(x)$ and number of situps a person can do $(y)$.
The results of the regression were:
$$\begin{array}{l}y=ax+b\\ a=-1.082\\ b=32.931\\ r^2=0.5625\\ r=-0.75\end{array}$$
Use this to predict the number of situps a person who watches 7.5 hour(s) of TV can do, and please round your answer to a whole number.

Step 1 ：The problem provides a regression equation in the form $y=ax+b$, where $y$ is the number of situps a person can do, $x$ is the number of hours of TV watched, $a$ is the slope of the line, and $b$ is the y-intercept.

Step 2 ：The given values are $a=-1.082$, $b=32.931$, and $x=7.5$.

Step 3 ：To predict the number of situps for a person who watches 7.5 hours of TV, we substitute $x=7.5$ into the equation and solve for $y$.

Step 4 ：Substituting the values into the equation gives $y=-1.082\ast 7.5+32.931$.

Step 5 ：Solving the equation gives $y=25$.

Step 6 ：Final Answer: The predicted number of situps a person who watches 7.5 hours of TV can do is $\boxed{{\displaystyle 25}}$.