Looking for an excel formula

Question

Engineers must consider the breadths of male heads when designing helmets. The company researchers have determined that the population of potential clientele have head breadths that are normally distributed with a mean of 6.9-in and a standard deviation of 0.8-in.

In what range would you expect to find the middle 68% of most head breadths?

Between  and .

If you were to draw samples of size 31 from this population, in what range would you expect to find the middle 68% of most averages for the breadths of male heads in the sample?

Between  and .

Enter your answers as numbers. Your answers should be accurate to 2 decimal places

Answer 1

middle 68% of most head breaths between mean +/- one standard deviation

middle 68% of mean heat breaths between mean +/- one standard deviation/sqrt(sample size)