In: Statistics and Probability
How much do college administrators (not teachers or service personnel) make each year? Suppose you read the local newspaper and find that the average annual salary of administrators in the local college is x = $58,940. Assume that σ is known to be $18,340 for college administrator salaries.
(a) Suppose that x = $58,940 is based on a random sample of n = 36 administrators. Find a 90% confidence interval for the population mean annual salary of local college administrators. What is the margin of error? (Round your answers to the nearest whole number.)
lower limit | $ |
upper limit | $ |
margin of error | $ |
(b) Suppose that x = $58,940 is based on a random sample
of n = 81 administrators. Find a 90% confidence interval
for the population mean annual salary of local college
administrators. What is the margin of error? (Round your answers to
the nearest whole number.)
lower limit | $ |
upper limit | $ |
margin of error | $ |
(c) Suppose that x = $58,940 is based on a random sample
of n = 121 administrators. Find a 90% confidence interval
for the population mean annual salary of local college
administrators. What is the margin of error? (Round your answers to
the nearest whole number.)
lower limit | $ |
upper limit | $ |
margin of error | $ |