Emirates Airline offers one outbound flight from Dubai, United Arab Emirates, to Doha, Qatar, and one return flight from Doha to Dubai each day. An experienced Emirates pilot suspects that the Dubai-to Doha outbound flight typically takes longer. To find out, the pilot collects data about these flights on a random sample of 12 days. The table displays the flight times in minutes.

a. Explain why these are paired data.

b. A dotplot of the difference (Outbound – Return) in flight time for each day is shown. Describe what the graph reveals about whether the outbound or return flight takes longer, on average.

c. Calculate the mean difference and the standard deviation of the differences. Interpret the standard deviation.

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Day 1 3 4 5 6 7 9 10 11 12 Outbound (Dubai 305 0.200 = 20.0% 1526 75 42 62 63 54 46 52 50 42 46 43 52 %3D Doha) Return (Doha → 305 42 37 37 44 42 40 41 44 41 42 48 48 0.200 = 20.0% 1526 Dubai)