Recently, 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 is $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)). Here, Z is 1.96 for 95% confidence, σ is $2,500, and n is 400. This gives $25,000 ± (1.96 * ($2,500/√400)) = $25,000 ± $245, resulting in the interval [$24,755, $25,245].

Recently, a University Surveyed Recent Graduates of the English Department