TABLE 12-18
Two new different models of compact SUVs have just arrived at the market. You are interested in comparing the gas mileage performance of both models to see if they are the same. A partial computer output for twelve compact SUVs of model 1 and thirteen of model 2 is given below:

You are told that the gas mileage population distributions for both models are not normally distributed.
-Referring to Table 12-18, what should be the null and alternative hypotheses of the test?

Question

TABLE 12-18
Two new different models of compact SUVs have just arrived at the market. You are interested in comparing the gas mileage performance of both models to see if they are the same. A partial computer output for twelve compact SUVs of model 1 and thirteen of model 2 is given below:
  
You are told that the gas mileage population distributions for both models are not normally distributed.
-Referring to Table 12-18, what should be the null and alternative hypotheses of the test?
A) H₀: M₁ = M₂ vs. H₁: M₁ ≠ M₂ 
B) H₀: M₁ ≥ M₂ vs. H₁: M₁ < M₂ 
C) H₀: M₁ ≤ M₂ vs. H₁: M₁ > M₂ 
D) H₀: M₁ ≠ M₂ vs. H₁: M₁ = M₂

Quizplus · Accepted Answer

Since we are interested in comparing the gas mileage performance of two different models, the null hypothesis should state that the mean gas mileage of both models is the same (M₁ = M₂), while the alternative hypothesis states that the mean gas mileage is different between the two models (M₁ ≠ M₂). This makes option A the correct choice. Option B is incorrect because we are not testing for one model being better than the other, but rather comparing the means. Option C is also incorrect for the same reason as option B. Option D is incorrect because it states the null and alternative hypotheses as being the same.

TABLE 12-18 Two New Different Models of Compact SUVs Have Just Arrived