Answer:
Explanation:
We want to determine a 95% confidence interval for the average time spent by male runners in a week in preparing for races.
Number of sample, n = 28
Mean, u = 22 hours
Standard deviation, s = 2 hours
For a confidence level of 95%, the corresponding z value is 1.96. This is determined from the normal distribution table.
We will apply the formula
Confidence interval
= mean ± z ×standard deviation/√n
It becomes
22 ± 1.96 × 2/√28
= 22 ± 1.96 × 0.378
= 22 ± 0.741
The lower end of the confidence interval is 22 - 0.741 =21.259
The upper end of the confidence interval is 22 + 0.741 =22.741