Answer:
Step-by-step explanation:
We want to determine a 95% confidence interval for the true population mean textbook weight.
Number of sample, n = 40
Mean, u = 52 ounces
Standard deviation, s = 5.4 ounces
For a confidence level of 95%, the corresponding z value is 1.96.
We will apply the formula
Confidence interval
= mean ± z ×standard deviation/√n
It becomes
52 ± 1.96 × 5.4/√40
= 52 ± 1.96 × 0.85
= 52 ± 1.666
The lower end of the confidence interval is 52 - 1.666 = 50.33 ounces
The upper end of the confidence interval is 52 + 1.666 = 53.67 ounces
Therefore, with 95% confidence interval, the true population mean textbook weight is between 50.33 ounces and 53.67 ounces
