Question

In a normal distribution what percent of values fall within one standard deviation of the mean?

Answer 1

Roughly 68% of the distribution is between z = -1 and z = +1, ie within 1 standard deviation of the mean. This is from the 68-95-99.7 rule or better known as the Empirical Rule. 

The final answer is choice D) 68.2%

Answer 2

if a normal distribution, what percentage of the data falls within 2 standard deviation of the mean.... c. 95% apex..