Answer:
Step-by-step explanation:
We want to determine a 99% confidence interval for the mean repair cost for the TVs
Number of sample, n = 17
Mean, u = $76.76
Standard deviation, s = $24.02
For a confidence level of 99%, the corresponding z value is 2.58. This is determined from the normal distribution table.
We will apply the formula
Confidence interval
= mean ± z ×standard deviation/√n
It becomes
76.76 ± 2.58 × 24.02/√17
= 76.76 ± 2.58 × 5.83
= 76.76 ± 15.03
The lower end of the confidence interval is 76.76 - 15.03 = $61.73
The upper end of the confidence interval is 76.76 + 15.03 = $91.79
Therefore, with 99% confidence interval, the mean repair cost for the TVs is between $61.73 and $91.79
