Answer
$s_{b_1}=0.00854$
Work Step by Step
$s_e=1.424$ (item (b))
To find $s_x$:
Using the EXCEL, enter the "Credit Score" values in the column A.
In A7 enter "=STDEV.S(A1:A6)"
$s_x=74.543$
$s_{b_1}=\frac{s_e}{\sqrt {∑(x_i-x ̅)^2}}=\frac{s_e}{\sqrt {n-1}s_x}$ (see note on page 684)
$s_{b_1}=\frac{1.424}{\sqrt {6-1}\times74.543}=0.00854$
