Question

A study was conducted to estimate hospital costs for accident victims who wore seat belts. Twenty randomly selected cases have a distribution that appears to be approximately​ bell-shaped with a mean of

​$9 comma 0039,003

and a standard deviation of

​$5 comma 6455,645.

Use the t distribution to construct the confidence interval estimate of the population mean.

Find the​ 95% confidence interval.

​$nothing less than<muμless than<​$nothing

Answer 1

df = n - 1 = 20 - 1 = 19

t critical value at 0.05 significance level with 19 df = 2.093

95% confidence interval for is

- t * S / sqrt(n) / n < < + t * S / sqrt(n) / n

9003 - 2.093 * 5645 / sqrt(20) < < 9003 + 2.093 * 5645 / sqrt(20)

6361.09 < < 11644.91

OR

6361 < < 11645 (Rounded to nearest integer)