Question

In Ms. Chang’s class, Emile found out that his walking rate is 2.5 meters per second. That means, Emile walks 2.5 meters every 1 second. When he gets home from school, he times his little brother Henri as Henri walks 100 meters. He figures out that Henri’s walking rate is 1 meter per second. Henri walks 1 meter very second.

Henri challenges Emile to a walking race. Because Emile’s walking rate is faster, Emile gives Henri a 45-meter head start. Emile knows his brother would enjoy winning the race, but he does not want to make the race so short that it is obvious his brother will win.

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


B Describe your strategy for finding your answer to Question A. Give evidence to support your answer.

Answer 1

Answer: A. The race should be 55 seconds long so that Henri will win in a close race.

Step-by-step explanation:

B. Speed of Henri = 1 metre/ 1 second

   Speed of Emile = 2.5 metres/ 1 second

   Head start Emile gave to Henri = 45-metres

   Distance from Emile's school to his home = 100 metres

   = 100 metres - 45 metres

   = 55 metres

   Time Henri will take to reach home = 1 metre/ second * 55 metres

                                                           = 55 seconds

   Time Emile will take to reach home = 2.5 metre/second * 100 metres

                                                            = 250

   Time Emile will take to let Henri win a close race = 250 - 55

                                                                                = 195 seconds

    Ans = Henri will take 55 seconds to win a close race.