Average speed for the entire journey was 62 miles per hour.
Total time of the journey was 5 hours.
In first 2 hours, her average speed was 60 miles per hour. This means, she covered 120 miles in first two hours, as
Distance = Speed x Time
The total distance of the entire journey was:
Total Distance = 62 x 5 =310 miles
Out of these 310 miles, she covered 120 miles in first two hours. So this means she covered (310 - 120) miles in next 3 hours.
Thus she covered 190 miles in 3 hours. So her average speed will be 190/3 miles per hour which is equal to 63.33 miles per hour.
So, the average speed for last 3 hours of the trip was 63.33 miles per hour
