Question

or Exercises 5 through 20, assume that all variables are approximately normally distributed. Stress Test Results For a group of 12 men subjected to a stress test situation, the average heart rate was 109 beats per minute. The standard deviation was 4. Find the 99% confidence interval of the population mean.

Answer 1

Solution :

Given that,

Point estimate = sample mean = = 109

sample standard deviation = s = 4

sample size = n = 12

Degrees of freedom = df = n - 1 = 12- 1 = 11

At 99% confidence level

= 1-0.99% =1-0.99 =0.01

/2 =0.01/ 2= 0.005

t/2,df = t_{0.005,11 = 3.11}

t _/2,df = 3.11

Margin of error = E = t_/2,df * (s /n)

= 3.11 * (4 / 12)

Margin of error = E =3.59

The 99% confidence interval estimate of the population mean is,

- E < < + E

109-3.59 < < 109+3.59

105.41< < 112.59

(105.41,112.59)

(,)