Answer
Margin of Error $\approx$ 0.675
Work Step by Step
The z score that corresponds to the confidence level 0.95 is 1.645.
Using z = 1.645, $\sigma$ = 2.9, n = 50 , margin of Error is given by:
z x $\frac{\sigma}{\sqrt n}$
1.645 x $\frac{2.9}{\sqrt 50}$
$\approx$ 0.675