Question

In: Statistics and Probability

A random sample of the price of gasoline from 30 gas stations in a region gives...

A random sample of the price of gasoline from 30 gas stations in a region gives the statistics below.

y overbary =​$3.293.29​,

s =​$0.24

a) Find a 95% confidence interval for the mean price of regular gasoline in that region.

b) Find the 90% confidence interval for the mean

c) If we had the same statistics from the sample of 80 stations, what would the 95% confidence interval be now?

Solutions

Expert Solution

a) The 95% confidence interval for the mean price of regular gasoline in that region is ,

; ; From Excel , =TINV(0.05,29)

b) The 90% confidence interval for the mean price of regular gasoline in that region is ,

; ; From Excel , =TINV(0.10,29)

c) Since , n=80

a) The 95% confidence interval for the mean price of regular gasoline in that region is ,

; ​​​​​​​ ; From Excel , =TINV(0.05,79)


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