Archie is fed up with waiting in line at his local post office and writes his congresswoman with his complaint. She stubbornly responds that, unless he can demonstrate that the mean waiting time at his branch is greater than 12 minutes (which is the threshold set by the federal government for urban branches), there is nothing she can do to help him. Over the course of the next few months, Archie records the waiting times for each of a random selection of 25 post office visits made by him and other customers. These waiting times (in minutes) are summarized in the following histogram: Frequency 10 - 10 8. 6 6. 2 2 2 6 12 18 24 30 Waiting time (in minutes) Based on the histogram, estimate the mean waiting time (in minutes) for Archie's sample. Carry your intermediate computations to at least four decimal places, and round your answer to at least one decimal place. X