The pulse rates of 148 randomly selected adult males vary from a low of 45 bpm to a high of 121 bpm. Find the minimum sample size required to estimate the mean pulse rate of adult males. Assume that we want 95% confidence that the sample mean is within 3 bpm of the population mean. Complete parts (a) through (c) below.

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

σ=

(Type whole number.)

**b. **Assume that sigma

σ=12.1 bpm, based on the value =12.1 bpm from the sample of 148 male pulse rates.=

(Typ whole number.)

**c. **Compare the results from parts (a) and (b). Which result is likely to be better?

The result from part (a) is larger than

the result from part (b). The result from part (b)

is likely to be better because it uses a better estimate of sigma .