Some manufacturers claim that non-hybrid sedan cars have a lower mean miles-per-gallon (mpg) than hybrid ones. Suppose that consumers test 254 hybrid sedans and get a mean of 26 mpg with a standard deviation of 4 mpg. Also, 237 non-hybrid sedans get a mean of 24 mpg with a standard deviation of 6 mpg. Suppose that both populations are known to be normal distributed. Conduct a hypothesis test to evaluate the manufacturers' claim. Test at a 4% level of significance. Let  population 1 denote non-hybrids and population 2 denote hybrids. (a)  H0 :  μ1 ______ μ2  (b)  Ha :  μ1 _______ μ2  (c) In words, state what your random variable represents.

Algebra & Trigonometry with Analytic Geometry
13th Edition
ISBN:9781133382119
Author:Swokowski
Publisher:Swokowski
Chapter10: Sequences, Series, And Probability
Section10.8: Probability
Problem 10E
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Some manufacturers claim that non-hybrid sedan cars have a lower mean miles-per-gallon (mpg) than hybrid ones. Suppose that consumers test 254 hybrid sedans and get a mean of 26 mpg with a standard deviation of 4 mpg. Also, 237 non-hybrid sedans get a mean of 24 mpg with a standard deviation of 6 mpg. Suppose that both populations are known to be normal distributed.

Conduct a hypothesis test to evaluate the manufacturers' claim. Test at a 4% level of significance.

Let  population 1 denote non-hybrids and population 2 denote hybrids.

(a)  H0 :  μ1 ______ μ2 

(b)  Ha :  μ1 _______ μ2 

(c) In words, state what your random variable represents.

The random variable is the (mean / difference in the / difference in the mean) miles per gallon of non-hybrid sedans and hybrid sedans.

 

(d) Select the distribution to use for the test.
o X1 - X2 ~ N [41 - 42,0]
o X1 - X2 ~ N (o, µ)
o taf
o X1 - X2 ~ N [4, o]
o X~ N[µ, 0]
Transcribed Image Text:(d) Select the distribution to use for the test. o X1 - X2 ~ N [41 - 42,0] o X1 - X2 ~ N (o, µ) o taf o X1 - X2 ~ N [4, o] o X~ N[µ, 0]
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