Answer
16%
Work Step by Step
$(35.8-33.7)/2.1 = (2.1/2.1) = 1$
We are looking for the percent of women who have arm lengths at least one standard deviation off the mean (on the lower tail).
Under the 68-95-99.7 rule, one deviation would fall under the 68%.
$100-68 = 32%$
However, this accounts for both tails, and we just want one tail. Thus, we can divide the 32% by 2 to get our desired answer of 16%.