The following model was fitted to a sample of 25 students using data obtained at the end of their freshman year in college. The aim was to explain students' weight gains:
$$
y_i=\beta_0+\beta_1 x_{1 i}+\beta_2 x_{2 i}+\beta_3 x_{3 i} \varepsilon_i
$$
where
$y_i=$ weight gained, in pounds, during freshman year
$x_{1 i}=$ average number of meals eaten per week
$x_{2 i}=$ average number of hours of exercise per week
$x_{3 i}=$ average number of beers consumed per week
The least squares estimates of the regression parameters were as follows:
$$
b_0=7.35 \quad b_1=0.653 \quad b_2=-1.345 \quad b_3=0.613
$$
a. Interpret the estimates $b_1, b_2$, and $b_3$.
b. Is it possible to provide a meaningful interpretation of the estimate $b_0$ ?