SOLUTION: It is claimed that automobiles are driven on average more than 20,000 kilometers per year. To test this claim, 100 randomly selected automobile owners are asked to keep a record of

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Question 1159396: It is claimed that automobiles are driven on average more than 20,000 kilometers per year. To test this claim, 100 randomly selected automobile owners are asked to keep a record of the kilometers they travel. Would you agree with this claim if the random sample showed an average of 23,500 kilometers and a standard deviation of 3900 kilometers?
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
Ho: d<=20,000 km/yr
Ha: d>20,000 km/year
alpha=0.05 P{reject Ho|Ho true}
test statistic is a t(0..95) df=99
Critical value t>1.66
calculation t=(x bar-mean)/s/sqrt (100)
t=3500*10/3900
t=8.97
strongly reject Ho and conclude that the vehicles are driven more than 20,000 km/year
P<0.0001 (about 10^(-15))