This function A(r) gives the average speed for an entire trip if the first half is traveled at 30 miles per hour and the second half is traveled at the speed indicated on the slider. The challenge is to determine the proper speed for the second half so that the average speed for the entire trip is 60 miles per hour. Move the slider to see. Good luck!

Move the slider at the top the change the speed for the second half of the trip.
Input the total length of the trip in the box below the graph to see the total time for the trip.