#22 Repair Costs: Vacuum Cleaners You want to buy a vacuum cleaner, and a salesperson tells
you the repair costs for Model A and Model B are equal. You research the repair costs of 34
Model A vacuum cleaners and 46 Model B vacuum cleaners. The results of you research are
shown below. At a=1.01, can you reject the salesperson's claim?
Model A Model B
x =$50 x =$60
s =$10 s =$15
Solution
Ans:
Test Statistic, t=(x-bar1 - x-bar2)/(s1^2/n1 +s2^2/n2)
=(50 - 60)/(10^2/34 + 18^2/46)
=-3.16470
Not eq. vars: No Pool (and df calculated with Formula 9-1)
Claim µ1 = µ2
Test Statistic, t: -3.1647
Critical t: ±2.644816
P-Value: 0.0023
Degrees of freedom: 73.0571
99% Confidence interval:
-18.35722 < µ1-µ2 < -1.642777
Reject the Null Hypothesis
Sample provides evidence to reject the claim.
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