Final answer:
Approximately 68 percent of the data lies within one standard deviation of the mean.
Step-by-step explanation:
The percent of data that lies within plus/minus one standard deviation from the mean in a normal distribution is approximately 68 percent. This is known as the Empirical Rule, which states that for data that is bell-shaped and symmetric, about 68 percent of the data is within one standard deviation of the mean. An example of this is if we have a normal distribution with a mean of 50 and a standard deviation of 6, approximately 68 percent of the values will lie between 44 and 56.