99% = mean ± 2.575 SEm
SEm = SD/√n
The makers of the MAGNETIZER Engine Energizer System (EES) claim that it improves gas mileage and reduces emissions in automobiles by using magnetic free energy to increase the amount of oxygen in the fuel for greater combustion efficiency. Following are test results, performed under International and U.S. Government agency standards, on a random sample of 14 vehicles. The data give the carbon monoxide (CO) levels, in parts per million, of each vehicle tested, both before installation of EES and after installation. [SOURCE: Global Source Marketing.]
Suppose that you want to perform a hypothesis test to determine whether, on average, EES reduces CO emissions.
What is the upper and lower bound for the 99% confidence interval for the change in emissions following the installation of the MAGENTIZER system (before - after)? Show two decimal places in your answer
Thank you in advance!
1 answer