read question in description

Question

if you take a 40 mile trip and you go 10mph for the first half of the trip, how fast would you have to go on the second half of the trip to average 20 mph for the entire trip.

Answer 1

Hello,

If the total distance covered was 40 miles and the average speed was 20 mph then
the total time for the entire trip was 40 miles / 20 mph = 2 hours.

If by "first half of the trip", they mean the first 20 miles, then since the speed for the 1st half is 10mph then
the time it takes to travel the first 20 miles has to be 20miles/10mph = 2 hours.
This doesn't make sense. 

 

So I assume that the "first half of the trip" means the first hour. Since you travel at 10 miles per hour for the first hour, then you travelled 10 miles which leaves 30 miles to be covered in the 2nd hour. 

 

As a result, you need to move at 30 miles per hour in the 2nd half to reach the destination.