Uber uses average Estimated Time of Arrival (ETA, waiting time of requested ride) to monitor the wellbeing of ridesharing market. An experiment is carried out where 30 users are randomly selected to test the effectiveness of the pricing algorithm on reducing ETA during rush hour. The users are matched into pairs based on demographic characteristics. For each pair, one user is randomly selected to use the new Uber app with the pricing algorithm implemented, while the other uses the old Uber app without the pricing algorithm. All users are asked to request a ride. The ETA (in minutes) of all users, as well as their mean and standard deviation, are recorded in the table below. Pricing Pair 1 Pair 2 . . Pair 15 Mean St Dev algorithm? Yes 9.3 4.8 . .. 8 5.7 0.8 No 7.4 8.4 ... 9 7.8 0.7 Diff (Yes-No) 1.9 -3.6 -1 -1.35 3.13 Histograms for each of three rows of the data indicates that they are reasonably close to being normally distributed. Calculate the appropriate test statistic to test the hypothesis Ho : Md = 0 vs. HA : Ma