SOLUTION: the population standard deviation fro a gas mileage for a certain model of car is known to be 1.8 miles per gallon. how many cars would you have to test(what sample would you need)

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Question 857153: the population standard deviation fro a gas mileage for a certain model of car is known to be 1.8 miles per gallon. how many cars would you have to test(what sample would you need)to get a margin of error of 0.5 mile per gallon (or less) for the population mean at a 90%confidence level?
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 
Hi,
90% z =1.645
92% z = 1.751
95% z = 1.96
98% z = 2.326
99% z = 2.576
ME = .5 =+1.645%281.8%2Fsqrt%28n%29%29%29
sqrt(n) = 1.645*1.8/.5 = 5.922
n= 35.07 0r approximately 36