Question

On Jiamin's trip to Wisconsin, her average rate of speed for the whole 5-hour trip was 62 miles per hour. For the first two hours of her trip, she kept her average speed at 60 miles per hour. Then she realized she was going to be late, so she started driving faster. What was her average speed for the last three hours of her trip?

Answer 1

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