QUESTION 2
Petronas has developed two blends of gasoline. Managers are interested in estimating the difference in mean gasoline mileage that will be obtained from using the two blends. As part of their study, they have decided to run a test using the Chevrolet Impala automobile with automatic transmissions. They selected a random sample of 100 Impalas using Blend 1 and another 100 Impalas using Blend 2. Each car was first emptied of all the gasoline in its tank and then filled with the designated blend of the new gasoline. The car was then driven 200 miles on a specified route involving both city and highway roads. The cars were then filled and the actual miles per gallon were recorded. The following summary data were recorded:
Blend 1 
Blend 2 

Sample Size 
100 
100 
Sample Mean 
23.4 mpg 
25.7 mpg 
Sample St. Dev. 
4.0 mpg 
4.2 mpg 
Worker 
1 
2 
3 
4 
5 
6 
7 
Before 
18 
23 
25 
22 
20 
21 
19 
After 
22 
25 
27 
25 
24 
19 
20 
Does the training program effective? Shows your working to support your answer.
Answer a) (3.444, 1.156)
Answer b)
At 0.05 significance level, there is enough evidence to conclude that the training program is effective.
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