John and Al are in a 15 km race. John averages 4.4 m/s during the first half of the race and then runs at a speed of 4.2 m/s until the last 200 m, which he covers at 4.5 m/s. At what average speed must Al run to beat John?

Question

The textbook that included the word problem is: Basic Biomechanics Sixth Edition by Susan J. Hall;
ISBN#978-0-07-337644-8

The course name: Biomechanics

Answer 1

I did this one for you yesterday

http://www.jiskha.com/display.cgi?id=1380495886

Please check back to your previous post before reposting the same question.
It really helps to avoid duplication of answers.

Answer 2

> 4.3 m/s