For example $6\mathrm{.}8$: What is the value of Maximum Shear Stress?

$($b$)Q$ for N$.$A$.$

$($a$)$ Cross$-$Section

$19\mathrm{.}56$MPa

$17\mathrm{.}13$ MPa

$18\mathrm{.}84$MPa

$21\mathrm{.}24$MPa