Mutate the data frame so that it includes a new variable that contains the average speed, avg$\_$speed traveled by the plane for each flight $($in mph$).$ Hint: Average speed can be calculated as distance divided by number of hours of travel, and note that air$\_$time is given in minutes.

Make a scatterplot of avg$\_$speed vs$.$ distance. Describe the relationship between average speed and distance. Hint: Use geom$\_$point$().$

Replicate the following plot. Hint: The data frame plotted only contains flights from American Airlines, Delta Airlines, and United Airlines, and the points are colored by carrier. Once you replicate the plot, determine $($roughly$)$ what the cutoff point is for departure delays where you can still expect to have a reasonable chance to get to your destination on time.