In: Statistics and Probability
A simple random sample of 40 colleges and universities in the United States has a mean tuition of 18,800 with a standard deviation of 10,100. Construct a 98% confidence interval for the mean tuition for all colleges and universities in the United States. Round the answers to the nearest whole number.
Solution :
sample size = n = 40
Degrees of freedom = df = n - 1 = 39
t /2,df = 2.426
Margin of error = E = t/2,df * (s /n)
= 2.426 * (10,100 / 40)
Margin of error = E = 3874.2
The 95% confidence interval estimate of the population mean is,
- E < < + E
18,800 - 3,874.2 < < 18,800 + 3,874.2
14,925.8 < < 22,674.2
(14,925.8, 22,674.2)