Question

A sample of 17 randomly selected student cars have ages with a mean of 7.8 years and a standard deviation of 3.63 years, while a sample of 22 randomly selected faculty cars have ages with a mean of 5.6 years and a standard deviation of 3.3 years.

1. Use a 0.05 significance level to test the claim that student cars are older than faculty cars.

(a) The test statistic is

(b) The critical value is

(c) Is there sufficient evidence to support the claim that student cars are older than faculty cars?

A. Yes
B. No


2. Construct a 95% confidence interval estimate of the difference μs−μf, where μsμs is the mean age of student cars and μf is the mean age of faculty cars.
? <(μs−μf)< ?

Answer 1

1a)

a) test statsitic =5.5652

b) critical value =1.6883

c) YEs

2)

Point estimate of differnce =x1-x2=			18.060
for 95 % CI & 36 df value of t=			2.028
margin of error E=t*std error   =			6.5813
lower bound=mean difference-E=			11.4784
Upper bound=mean differnce +E=			24.6416

from above 95% confidence interval for population mean =(11.4784 ,24.6416)