SOLUTION: Another one I am stuck on. I used two different formulas...one with z scores, one with normdist. But they came out different. (One was0.412526 and the other 0.1131). Can you please

Question 373746: Another one I am stuck on. I used two different formulas...one with z scores, one with normdist. But they came out different. (One was0.412526 and the other 0.1131). Can you please help with this problem?
Thanks!
The manufacturer of a new compact car claims the miles per gallon (mpg) for the gasoline consumption is mound shaped and symmetric with a mean of 25.9 mpg and a standard deviation of 9.5 mpg. If 30 such cars are tested, what is the probability the average mpg achieved by these 30 cars will be greater than 28? Place your answer, rounded to 4 decimal places, in the blank. _______
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
Hint: Find the distribution for Xbar (the sample mean) and you'll find that it is a normal curve. From there, find the area under the curve from 28 and to the right onward.
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