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In a sample of seven cars, each car was tested for nitrogen oxide emissions in g

ID: 3023336 • Letter: I

Question

In a sample of seven cars, each car was tested for nitrogen oxide emissions in grams per mile and the folo ng results were obtained 0.18, 13, 0.1 0 15 0.09, 0.09, 0.16 Assuming hat his sample is representative of the cars in use, construct a 98% confidence interval estimate o he mean amount of nitrogen oxide emissions or all cars. If the EPA requires that nitrogen oxide emissions be less than 0.165 g / mi can we sate conclude that this requirement is being met? Click here to view a t distribution table. Click here to view page 1 of the standard normal distribution table. er iew page 2 of t tandard normal distribution table What is the confidence interval estimate of the mean amount of nitrogen-oxide emissions for all cars? Round to three decimal places as needed.) Can we safely conclude that the requirement that nitrogen-oxide emissions be less than 0.165 g/mi is being met? O A. O B. ° C. 0 D. Yes, we can definitely conclude that the requirement is met for all cars. No, because the confidence interval does not contain 0 165 g/ml. No, it is possible that the requirement is being met, but it is also very possible that the mean is not less than 0.165 g/mi. Yes, because the confidence interval contains 0.165 g / mi.

Explanation / Answer

Note that              
              
Lower Bound = X - t(alpha/2) * s / sqrt(n)              
Upper Bound = X + t(alpha/2) * s / sqrt(n)              
              
where              
alpha/2 = (1 - confidence level)/2 =    0.01          
X = sample mean =    0.13          
t(alpha/2) = critical t for the confidence interval =    3.142668403          
s = sample standard deviation =    0.035118846          
n = sample size =    7          
df = n - 1 =    6          
Thus,              
              
Lower bound =    0.088285238          
Upper bound =    0.171714762          
              
Thus, the confidence interval is              
              
(   0.088285238   ,   0.171714762   ) [ANSWER]

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As we can see, 0.165 is inside this interval. Hence,

OPTION C: No, it is possible that the requirement is being met, but it is also very possible that the mean is not less than 0.165 g/mi. [ANSWER]

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