the u.s. energy information administration (us eia) reported that the average price for a gallon of regular gasoline is $2.94. the us eia updates its estimates of average gas prices on a weekly basis. assume the standard deviation is $.25 for the price of a gallon of regular gasoline and recommend the appropriate sample size for the us eia to use if they wish to report each of the following margins of error at 95% confidence. a. the desired margin of error is $.10. b. the desired margin of error is $.07. c. the desired margin of error is $.05