How to identify characteristics of a normal distribution Practice Test

Which parameters define the normal distribution?

In order to be considered a normal distribution, a data set (when graphed) must follow a bell-shaped symmetrical curve centered around the mean.

It must also adhere to the empirical rule that indicates the percentage of the data set that falls within (plus or minus) 1, 2 and 3 standard deviations of the mean.

In order to be a normal distribution, what percentage of the data set must fall within: