Question

Buffalo	Boston
26	23
27	14
39	11
23	19
17	19
16	4
21	9
31	12
1	12
23	7
32	32
32	26
24	21
42	16
38	16
29	18
16	16
12	20
29	20
16	11
18	10
27	18
2	11
21	17
35	20
21	20
29	25
24	16
17	17
21	8
38
21
9
24
31
26
16
27
24
18
24
17
13
15
21
21
21
32
27
35

Round your answers to one decimal place.

1. What is the point estimate of the difference between the mean number of miles that Buffalo residents travel per day and the mean number of miles that Boston residents travel per day?

2. What is the 95% confidence interval for the difference between the two population means?

Answer 1

	Buffalo ( X )		Boston ( Y )
	26	6.8644	23	45.3373
	27	13.1044	14	5.1379
	39	243.9844	11	27.7381
	23	0.1444	19	7.4709
	17	40.7044	19	7.4709
	16	54.4644	4	150.4719
	21	5.6644	9	52.8049
	31	58.0644	12	18.2047
	1	500.8644	12	18.2047
	23	0.1444	7	85.8717
	32	74.3044	32	247.5367
	32	74.3044	26	94.7371
	24	0.3844	21	22.4041
	42	346.7044	16	0.0711
	38	213.7444	16	0.0711
	29	31.5844	18	3.00
	16	54.4644	16	0.0711
	12	129.5044	20	13.9375
	29	31.5844	20	13.9375
	16	54.4644	11	27.7381
	18	28.9444	10	39.2715
	27	13.1044	18	3.0043
	2	457.1044	11	27.7381
	21	5.6644	17	0.5377
	35	135.0244	20	13.9375
	21	5.6644	20	13.9375
	29	31.5844	25	76.2705
	24	0.3844	16	0.0711
	17	40.7044	17	0.5377
	21	5.6644	8	68.3383
	38	213.7444
	21	5.6644
	9	206.7844
	24	0.3844
	31	58.0644
	26	6.8644
	16	54.4644
	27	13.1044
	24	0.3844
	18	28.9444
	24	0.3844
	17	40.7044
	13	107.7444
	15	70.2244
	21	5.6644
	21	5.6644
	21	5.6644
	32	74.3044
	27	13.1044
	35	135.0244
Total	1169	3705.78	488	1085.8658

Mean

Standard deviation

Mean

Standard deviation

Part a)

Point estimate = ( 23.38 - 16.2667 ) = 7.1

Part b)

Confidence interval :-



DF = 75
t_{\alpha /2, DF} = t_{ 0.05 /2, 75 } = 1.992

Lower Limit =
Lower Limit = 3.8034
Upper Limit =
Upper Limit = 10.4232
95% Confidence interval is ( 3.8 , 10.4 )