A university surveyed recent graduates of the English Department for their starting salaries. Four hundred graduates returned the survey. The average salary was $25,000. The population standard deviation was $2,500. What is the 95% confidence interval for the mean salary of all graduates from the English Department?
A) [$22,500, $27,500]
B) [$24,755, $25,245]
C) [$24,988, $25,012]
D) [$24,600, $25,600]

Question

Quizplus · Accepted Answer

The 95% confidence interval is calculated using the formula: mean ± (Z * (σ/√n)), where Z is the Z-score for 95% confidence (approximately 1.96), σ is the population standard deviation, and n is the sample size. Plugging in the values: $25,000 ± (1.96 * ($2,500/√400)) = $25,000 ± $245, which gives the interval [$24,755, $25,245].

A University Surveyed Recent Graduates of the English Department for Their