In order to estimate the average time spent per student on the computer terminals at a local university, data were collected for a sample of 81 business students over a one-week period.Assume the population standard deviation is 1.8 hours.If the sample mean is 9 hours, then the 95% confidence interval is
A) 7.04 to 10.96 hours.
B) 7.36 to 10.64 hours.
C) 7.80 to 10.20 hours.
D) 8.61 to 9.39 hours.

Question

In order to estimate the average time spent per student on the computer terminals at a local university, data were collected for a sample of 81 business students over a one-week period.Assume the population standard deviation is 1.8 hours.If the sample mean is 9 hours, then the 95% confidence interval is
A) ​7.04 to 10.96 hours.
B) ​7.36 to 10.64 hours.
C) ​7.80 to 10.20 hours.
D) ​8.61 to 9.39 hours.

Quizplus · Accepted Answer

The 95% confidence interval is calculated using the formula: sample mean ± (Z * (population standard deviation / sqrt(sample size))). With a Z-value of 1.96 for 95% confidence, the interval is 9 ± (1.96 * (1.8 / sqrt(81))), which simplifies to 8.61 to 9.39 hours.

In Order to Estimate the Average Time Spent Per Student