Question

Part I: Making the Race

Henri is Emile's younger brother and they are having a walking race. Emile can walk 2.5 meters per second whereas Henri walks 1 meter per second. Because Emile is faster, they give Henri a 45 meter head start. Emile knows Henri would enjoy winning the race, but they do not want to make the race so short that it is obvious Emile let Henri win.


1. How long should the race be so that Henri will win in a close race?

2. Describe or show your strategy on how you came up with your answer for #1.

Answer 1

74 meters

Explanation:

The difference in Emile and Henry's speed is 1.5, and the lead for Henry is 45 meters, so 45÷1.5= 30 seconds which means Henry will go another 30 meters at 1 meter per second.

2. To make it a close race we want Henry to go a longer distance than Emile, so make it 74 meters, which means Emile will go only have 45+29 = 74 seconds to get to 74 meters, but Henry only have 29 seconds in total = 29*2.5 = 72.5 meters.