Okay - So:
7 miles at 25mph = 16min 48 secs
14 miles at 40mph = 21 mins
21mins - 16.8 mins = 4.2mins
So the driver must do:
7miles in 4.2 mins = 100 mph (99.99999)
to average 40mph for the whole journey. Am I right?
Thank you for your reply. I had noticed that! However, given that 55mph is the wrong answer I still lack the tools to finish the job. Please could you tell me how to solve this, then I'll be equipped for life :)
[SOLVED] Average speed
Hi, Please could someone enlighten me as to how to solve the following, given that the total time of the journey is not given?
A commuter drives to work 14 miles. Due to traffic, the commuter averages 25 miles per hour on the first 7 miles of the drive. How fast must...