Question

In 2008, a small dealership leased 21 Subaru Outbacks on 2-year leases. When the cars were returned in 2010, the mileage was recorded (see below).

40,003	24,939	14,329	17,380	44,741	44,554	20,229
33,370	24,220	41,702	58,328	35,831	25,790	28,983
25,066	43,357	23,993	43,557	53,670	31,811	36,709

(a)	Is the dealer's mean significantly greater than the national average of 30,162 miles for 2-year leases? Using the 10 percent level of significance, choose the appropriate hypothesis.

a.	H0: μ ≤ 30,162 miles vs. H1: μ > 30,162 miles, reject H0 if tcalc > 1.3250
b.	H0: μ ≥ 30,162 miles vs. H1: μ > 30,162 miles, reject H0 if tcalc > 1.3250
c.	H0: μ ≤ 30,162 miles vs. H1: μ < 30,162 miles, reject H0 if tcalc > 1.3250
d.	H1: μ ≤ 30,162 miles vs. H0: μ > 30,162 miles, reject H0 if tcalc > 1.3250

	a b c d

(b)	Calculate the test statistic. (Round your answer to 2 decimal places.)

Test statistic

(c)	The dealer's cars show a significantly greater mean number of miles than the national average at the 10 percent level.
	Yes No

Answer 1

X : The mileage of care (in miles)

n=21

Sr. No.	X	X^2
1	40003	1600240009
2	24939	621953721
3	14329	205320241
4	17380	302064400
5	44741	2001757081
6	44554	1985058916
7	20229	409212441
8	33370	1113556900
9	24220	586608400
10	41702	1739056804
11	58328	3402155584
12	35831	1283860561
13	25790	665124100
14	28983	840014289
15	25066	628304356
16	43357	1879829449
17	23993	575664049
18	43557	1897212249
19	53670	2880468900
20	31811	1011939721
21	36709	1347550681
Total	712562	26976952852