Question

A sample data set with a mean of 685 and a standard deviation of 39.8 has a bell-shaped distribution. what range of values include approximately 68% of the data?
a. between 645.2 and 724.8
b. between 605.4 and 764.6
c. between 565.6 and 804.4
d. between 656.2 and 703.8

Answer 1

The correct choice is A) between 645.2 and 724.8.

According to the empirical rule, 68% of data will fall within 1 standard deviation from the mean.  This means it will be either 39.8 lower than the mean or 39.8 higher than the mean:
685-39.8 = 645.2
685+39.8 = 724.8