An industrial plant wants to determine which of two types of fuel, electric or gas, is more cost efficient (measured in cost per unit of energy). Independent random samples were taken of plants using electricity and plants using gas. These samples consisted of  15  plants using electricity, which had a mean cost per unit of  $66.7  and standard deviation of  $8.75 , and  8  plants using gas, which had a mean of  $59.4  and standard deviation of  $8.07  . Assume that the populations of costs per unit are normally distributed for each type of fuel, and assume that the variances of these populations are equal. Can we conclude, at the  0.1  level of significance, that the mean cost per unit for plants using electricity,  μ1 , is greater than the mean cost per unit for plants using gas,  μ2 ? Perform a one-tailed test.   The null hypothesis: H0:   The alternative hypothesis: H1:   The type of test statistic: (Choose one)ZtChi squareF             The value of the test statistic:(Round to at least three decimal places.)   The p-value:(Round to at least three decimal places.)   Can we conclude that the mean cost per unit for plants using electricity is greater than the mean cost per unit for plants using gas?   Yes     No

Glencoe Algebra 1, Student Edition, 9780079039897, 0079039898, 2018
18th Edition
ISBN:9780079039897
Author:Carter
Publisher:Carter
Chapter10: Statistics
Section10.4: Distributions Of Data
Problem 19PFA
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An industrial plant wants to determine which of two types of fuel, electric or gas, is more cost efficient (measured in cost per unit of energy). Independent random samples were taken of plants using electricity and plants using gas. These samples consisted of 

15

 plants using electricity, which had a mean cost per unit of 

$66.7

 and standard deviation of 

$8.75

, and 

8

 plants using gas, which had a mean of 

$59.4

 and standard deviation of 

$8.07

 . Assume that the populations of costs per unit are normally distributed for each type of fuel, and assume that the variances of these populations are equal. Can we conclude, at the 

0.1

 level of significance, that the mean cost per unit for plants using electricity, 

μ1

, is greater than the mean cost per unit for plants using gas, 

μ2

?

Perform a one-tailed test.

 
The null hypothesis:
H0:
 
The alternative hypothesis:
H1:
 
The type of test statistic: (Choose one)ZtChi squareF      
     
The value of the test statistic:
(Round to at least three decimal places.)
 
The p-value:
(Round to at least three decimal places.)
 
Can we conclude that the mean cost per unit for plants using electricity is greater than the mean cost per unit for plants using gas?
 
Yes
 
 
No
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