Congress regulates corporate fuel economy and sets an annual gas mileage for car

Question

Congress regulates corporate fuel economy and sets an annual gas mileage for cars. A company with a large fleet of cars hopes to meet the goal of 34.5 mpg or better for their fleet of cars. To see if the goal is being met, they check the gasoline usage for 27 company trips chosen at random, finding a mean of 36.50 mpg and a standard deviation of 5.26 mpg. Is this strong evidence that they have attained their fuel economy goal? Complete parts (a) through (f) below. Use 0.05 as the P-value cutof level a) Write appropriate hypotheses. (The mean fuel economy of all cars in the company's fleet is denoted by .) OA. Ho : -34.5 O B. Ho : #345 C. Ho : -34.5 D. Ho : -34.5 HA :34.5 HA: = 34.5 HA : -34.5 HA :

Explanation / Answer

Here' the answer in detail:

Firstly,

We will use the t distribution and not the Z ( normal ) distribution as the sample size is less than 30. It is 27 in our case.

Secondly, the claim or the goal will into the alternate hypothesis. i.e.

Ha: Mu>34.5
Hence, Ho; Mu = 34.5

Therefore, C is correct answer for a)

b) The 27 trips were chosen at random, so data is independent. First assumption is right.

A has the data is independent option and says that the distribution is Student' t-dist.

The 2nd part of the option explains the 2nd assumption that is needed.

Hence, A is correct for b)

c) df = n-1 = 27-1 = 26

Hence, t-statistic = tdf = t26 = (ybar-Population mean)/(Sample dev/sqrt(n)) = (ybar-34.5)/(s/sqrt(27)

A is right

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.