Answer:
Step-by-step explanation:
We want to construct a 90% confidence interval for the mean content of this brand of buffered aspirin.
Number of sample, n = 25
Mean, u = 325.05 mg
Standard deviation, s = 0.5 mg
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
325.05 ± 1.96 × 0.5/√25
= 325.05 ± 1.96 × 0.1
= 325.05 ± 0.196
The lower end of the confidence interval is 325.05 - 0.196 =324.854
The upper end of the confidence interval is 325.05 + 0.196 =325.246
Therefore, with 95% confidence interval, the mean content of this brand of buffered aspirin is between 324.854 mg and 325.246 mg
