led 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 13 minutes which is the threshold set for her district 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 27 post office visits made by him and other customers These waiting times in minutes are summarized in the following histogram Frequency 10 8 6 4 2 0 2 minut 0 6 6 ITE 9 14 20 7 13 Waiting time in minutes 3 21 27 28 34 Based on the histogram using the midpoint of each data class estimate the mean waiting time for Archie s sample Carry your intermediate computations to at least four decimal places and round your answer to one decimal place