Question

In 2022, a random sample of UGA students found that they slept an average of 7.43 hours per night. The margin of error for a 90% confidence interval was reported as 1.32 hours.

(a) What is the lower limit of this 90% confidence interval?
lower limit = (2 decimal places)

(b) If 500 random samples like this were selected, and a 90% confidence interval was constructed using each sample, approximately how many of these confidence intervals would contain the population mean?
(whole number)

Answer 1

Explanation:

(a) The lower limit of the 90% confidence interval can be calculated using the formula:

lower limit = sample mean - margin of error

Plugging in the given values, we have:

lower limit = 7.43 - 1.32

lower limit = 6.11 (rounded to 2 decimal places)

Therefore, the lower limit of the 90% confidence interval is approximately 6.11 hours per night.

(b) If 500 random samples like this were selected, and a 90% confidence interval was constructed using each sample, the expected number of intervals that would contain the population mean can be approximated using the margin of error as a guide.

Since the margin of error is 1.32 hours, we can expect roughly 90% of the confidence intervals to contain the true population mean. Therefore, out of 500 samples, we would expect approximately:

500 * 0.9 = 450

So, approximately 450 of these confidence intervals would contain the population mean.