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 for the mean can be calculated using the formula: mean ± (Z * (σ/√n)), where Z is the Z-score for a 95% confidence level (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, giving us the interval [$24,755, $25,245].

A University Surveyed Recent Graduates of the English Department for Their