In a simple random sample of 75 working adults in a city in Virginia, the average commute time for these workers was 23.65 minutes. The standard deviation from this sample was 18.50 minutes. A 95% confidence interval for the mean commute time for all adult workers in this city is approximately
A) 18.50 ± 2.73.
B) 18.50 ± 5.46.
C) 23.65 ± 4.187.
D) 23.65 ± 2.136.

Question

Quizplus · Accepted Answer

The 95% confidence interval for the mean commute time is calculated using the formula: mean ± (critical value) * (standard deviation / sqrt(sample size)). The critical value for a 95% confidence interval, assuming a normal distribution, is approximately 1.96. Thus, the margin of error is 1.96 * (18.50 / sqrt(75)), which is approximately 4.187. Therefore, the confidence interval is 23.65 ± 4.187.

In a Simple Random Sample of 75 Working Adults in a City