Question

he pulse rates of 160 randomly selected adult males vary from a low of 37 bpm to a high of 117 bpm. Find the minimum sample size required to estimate the mean pulse rate of adult males. Assume that we want 90​% confidence that the sample mean is within 2 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. n equals nothing ​(Round up to the nearest whole number as​ needed.)

Answer 1

Solution:

We have given that

The pulse rate varies from 37 bpm to 117 bpm.That is

Min =27 bpm

Max=117 bpm

We know that,

Sample Range=Max-Min=117-27=90

Now,by using range rule of thumb to estimate Sigma we know that,

= =   =22.5

Hence,

Standard Deviation =σ=22.5

We know that,

Margin of error=E=2 bpm

Confidence level=0.90 and.  =0.10

Now critical value for =0.10 is

Z  =1.64

Since we know the population standard deviation the formula for sample size is given by_,

n=[(Z*)/E]²

n = [1.64*22.5/2]²

n =18.45²

n=340.4025

By rounding to nearest integer we get

n=341

Therefore the

Sample Size=341