Answer
$s_{b_1}=0.150$
Work Step by Step
$s_e=0.494$ (item (b))
To find $s_x$:
Using the EXCEL, enter the "Right Humerus" values in column A.
In A12 enter "=STDEV.S(A1:A11)"
$s_x=1.041$
$s_{b_1}=\frac{s_e}{\sqrt {∑(x_i-x ̅)^2}}=\frac{s_e}{\sqrt {n-1}s_x}$ (see note on page 684)
$s_{b_1}=\frac{0.494}{\sqrt {11-1}\times1.041}=0.150$