The pulse rates of 146 randomly selected adult males vary from a low of 39 bpm to a high of 119 bpm. Find the minimum sample size required to estimate the mean pulse rate of adult males. Assume that...

The pulse rates of 146 randomly selected adult males vary from a low of 39 bpm to a high of 119 bpm. Find the minimum sample size required to estimate the mean pulse rate of adult males. Assume that we want 99​% confidence that the sample mean is within 4 bpm of the population mean.

a. Find the sample size using the range rule of thumb to estimate σ.