An automobile manufacturer claims that their car has a 40.5 miles/gallon (MPG) rating. An independent testing firm has been contracted to test the MPG for this car. After testing 170 cars, they found a mean MPG of 40.3. Assume the standard deviation is known to be 1.2. Is there sufficient evidence at the 0.02 level that the cars underperform the manufacturer's MPG rating? 1. What is the null and alternative hypothesis? 2. What is the z-test statistic (2 decimal places)? 3. One or two-tailed? 4. Reject Ho if Z < ______. 5. Reject or fail to reject?
Added by Roberto S.
Step 1
The null hypothesis (H0) is that the cars perform as the manufacturer claims, and the alternative hypothesis (H1) is that the cars underperform the manufacturer's claim. So, we have: H0: μ = 40.5 H1: μ < 40.5 Show more…
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