Question

Monthly rent paid by undergraduates and graduate students. Undergraduate Student Rents (n = 10) 800 760 860 690 680 790 820 670 1,030 700 Graduate Student Rents (n = 12) 1,080 870 880 900 760 930 720 830 950 910 870 860 PictureClick here for the Excel Data File (a) Construct a 99 percent confidence interval for the difference of mean monthly rent paid by undergraduates and graduate students, using the assumption of unequal variances with Welch's formula for d.f. (Do not round the intermediate calculations. Round your final answers to 3 decimal places. Negative values should

Answer 1

#### By using R command:

> x=c(800,760,860,690,680,790,820,670,1030,700)
> x###Undergraduate Student Rents
[1] 800 760 860 690 680 790 820 670 1030 700
> y=c(1080,870,880,900,760,930,720,830,950,910,870,860)
> y ###Graduate Student Rents
[1] 1080 870 880 900 760 930 720 830 950 910 870 860
> xbar=mean(x)
> xbar
[1] 780
> s1=var(x)## variance
> s1
[1] 12000
> ybar=mean(y)
> ybar
[1] 880
> s2=var(y)#### variance
> s2
[1] 8345.455

The 99% confidence interval for the difference of mean is given by

Where

Therefore,

The 99% confidence interval for the difference of mean is