b$)$ Now the bar is being re$-$designed, and it turns out that $D_{\text{m}\text{a}\text{x}}$ is constrained to be equal to $\frac{d_2}{2}.$ If this is the case, what distance b from the end $C$ should the load $P$ act to make sure that the shortening of the bar remains less than $8$ mni? $($Round to four decimals$)$