Question

Data collected by a price reporting agency from more than 90,000 gasoline and convenience stores throughout the U.S. showed that the average price for a gallon of unleaded gasoline was $3.28. The following data show the price per gallon ($) for a sample of 20 gasoline and convenience stores located in San Francisco.

3.59	3.59	4.59	3.76	3.75	3.71	3.65	3.80	3.55	3.36
3.57	3.79	3.55	4.19	3.95	3.46	3.83	3.93	3.41	3.37

a) Use the sample data to estimate the mean price for a gallon of unleaded gasoline in San Francisco.

b) Compute the sample standard deviation. (Round your answer to the nearest cent.)

c) Compare the mean price per gallon for the sample data to the national average price. What conclusions can you draw about the cost of living in San Francisco?

The average price for a gallon of unleaded gasoline in San Francisco is  ---Select--- higher than lower than same as the national average. This indicates that the cost of living in San Francisco is  ---Select--- higher than lower than same as it would be for cities that have an average price close to the national average.

Answer 1

We have n = 20 , ∑x = 74.4 and ∑( x - )² = 1.6356

a) Sample mean () = = 74.4 / 20

Sample mean price for a gallon of unleaded gasoline in San Francisco. () = 3.72  

b) sample standard deviation(s) = =

sample standard deviation(s) = 0.29

c)

The average price for a gallon of unleaded gasoline in San Francisco is  higher than the national average. This indicates that the cost of living in San Francisco is higher than would be for cities that have an average price close to the national average.