In 2008, a small dealership leased 21 Subaru Outbacks on 2-year leases. When the

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). 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. Calculate the test statistic. (Round your answer to 2 decimal places.) The dealer's cars show a significantly greater mean number of miles than the national average at the 10 percent level.

Explanation / Answer

a)

total number of values =21

hence degree of freedom =n-1 =20

for 20 degree of freedom and right tailed t test at 10% level, tcritical =1.325

a)option a is correct as we are looking if mean is greater then 30162.

b)here as std error =std deviation/(n)1/2 =2581.361

tstat =(Xbar -mean)/std error =(33931.52-30162)/2581.361 =1.46

c)a s tstat is greater then t critical; we accept dealer's claim that it show greater mean number of miles.

hence Yes

X 40003 24939 14329 17380 44741 44554 20229 33370 24220 41702 58328 35831 25790 28983 25066 43357 23993 43557 53670 31811 36709 Xbar 33931.52 std deviation 11829.28

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