Answer
Margin of error $\approx$ 0.192
Work Step by Step
The z score that corresponds to the confidence level 0.80 is 1.28.
Using z = 1.28, $\sigma$ = 1.3, n = 75 , margin of Error is given by:
z x $\frac{\sigma}{\sqrt n}$
1.28 x $\frac{1.3}{\sqrt 75}$
$\approx$ 0.192