Question

In an effort to learn more about newspaper readers, an advertiser selected a random sample of people who purchase their paper from a street vendor and a separate random sample of those who have the paper delivered. Each was asked how many minutes they spend reading the paper on a typical day. Estimate, with 90% confidence, the difference in mean times spent reading the paper is:

Data Set :

In an effort to learn more about newspaper readers, an advertiser selected a random sample of people who purchase their paper from a street vendor and a separate random sample of those who have the paper delivered. Each was asked how many minutes they spend reading the paper on a typical day. The data are stored in file: NEWSPAPER.MTW. Estimate, with 90% confidence, the difference in mean times spent reading the paper is:

Vendor   Delivered
17   19.4
19   22.4
14   11.4
23   18.4
15   17.4
22   22.4
12   26.4
17   14.4
23   24.4
22   23.4
18   26.4
21   14.4
24   20.4
24   13.4
12   20.4
18   22.4
28   24.4
17   18.4
17   20.4
19   22.4
22   31.4
17   20.4
17   17.4
21   15.4
29   17.4
27   21.4
21   25.4
17   22.4
21   20.4
21   21.4
24   22.4
22   16.4
18   26.4
18   19.4
16   24.4
21   21.4
17   20.4
19   20.4
27   20.4
21   16.4
20   23.4
22   25.4
13   18.4
5   16.4
24   22.4
22   14.4
17   17.4
29   19.4
15   22.4
15   14.4
20   17.4
18   13.4
16   20.4
20   19.4
15   14.4
20   19.4
25   22.4
14   18.4
26   26.4
22   22.4
20   24.4
20   23.4
22   21.4
20   12.4
23   21.4
13   19.4
23   19.4
18   23.4
21   23.4
20   21.4
15   22.4
24   20.4
23   20.4
19   22.4
21   16.4
19   23.4
21   13.4
17   14.4
19   17.4
20   27.4
19   13.4
16   27.4
23   20.4
23   18.4
21   22.4
18   20.4
18   16.4
19   11.4
24   15.4
20   23.4
20   22.4
12   23.4
19   17.4
20   22.4
19   24.4
20   19.4
14   22.4
23   19.4
15   24.4
18   17.4
19   17.4
23   22.4
21   17.4
24   24.4
17   21.4
23   19.4
19   29.4
19   17.4
23   25.4
21   18.4
14   22.4
20   15.4
21   16.4
19   25.4
17   19.4
18   17.4
26   24.4
14   24.4
10   19.4
13   21.4
22   19.4
24   24.4
17   19.4
18   25.4
16   22.4
20   24.4
25   15.4
14   18.4
20   28.4
22   25.4
16   20.4
15   21.4
21   24.4
22   15.4
20   17.4
21   21.4
22   15.4
21   13.4
16   22.4
23   21.4
14   24.4
26   26.4
19   18.4
22   19.4
14   18.4
19   26.4
26   15.4
19   21.4
17   19.4
17   16.4
20   22.4
13   16.4
19   26.4
22   19.4
25   18.4
16  
18  
24  
16  
20  
19  
22  
17  
30  
24  
14  
18  
21  
16  
26  
22  
19  
15  
17  
12  
15  
24  
22  
21  
21  
19  
17  
20  
13  
19  
23  
20  
16  
20  
16  
21  
18  
27  
21  
24  
23  
20  
19  
17  
20  
20  
14  
21  
20  
18  

Answer 1

First we need to find the mean and SD of both data sets. Following is the output of descriptive statistics:

Descriptive statistics
	Vendor, X1	Delivered, X2
count	205	155
mean	19.50	20.426
sample standard deviation	3.79	3.870
sample variance	14.35	14.973
minimum	5	11.4
maximum	30	31.4
range	25	20

Following is the required confidence interval:

Answer: (-1.597, -0.255)