Answer
$F_0=12.70$ with a P-value $\ltα$. Reject the null hypothesis.
There is enough evidence to conclude that there exists a linear relation between at least one of the explanatory variables and the 28-day strength.
Work Step by Step
$H_0: β_1=β_2=0$ versus $H_1: at~least~one~β_i\ne0$
See the results obtained in item (b)
$F_0=12.70$ with a P-value $=0.003\ltα=0.05$
