Instead of hearing the jingle of prices being rung up manually on cash registers, we now hear the beep of prices being scanned by electronic scanners. How accurate is price scanning? There are errors, and according to a Denver Post article, when the error occurs in the store’s favor, it is larger than when it occurs in the customer’s favor. An investigation of large discount stores by the Colorado state inspectors showed that the average error in the store’s favor was $2.66. Assume that the distribution of scanner errors is more or less mound-shaped. If the standard deviation of scanner errors (in the store’s favor) is $0.85, use the empirical rule to
(a) estimate a range of scanner errors centered about the mean in which 68% of the errors will lie.
(b) estimate a range of scanner errors centered about the mean in which 95% of the errors will lie.
(c) estimate a range of scanner errors centered about the mean in which almost all the errors will lie.