Question

what percent of people within 3 standard deviations of the mean?

Explanation:

Step1: Identify relevant areas

In a normal - distribution curve, we need to sum the areas within $\mu - 3\sigma$ and $\mu+3\sigma$.

Step2: Sum the percentages

$(0.15 + 2.35+13.5 + 34+34 + 13.5+2.35 + 0.15)\%=99.7\%$

Answer:

99.7