#2             65. YOU AND I AND ...                  

“My sister is travelling overseas,” Bessie confided to her friend Thel. “She is leaving at 11 a.m., that is, exactly two hours from now. I would like to see her before she leaves. Let’s see, it is 160 kilometres. We would have to average 80 km/hr. Come on, we can do that easily.”

So they set off. But the traffic was heavy, and when they reached the half-way mark, they found they had only averaged 40 km/hr.

“We’ll have to do better than this,” said Bessie. “Fortunately, we have a clear road in front of us.”

What average speed should Bessie travel for the rest of the trip if she is to reach her destination in time?
Hints and strategies

Hint 1           Hint 2            Solution             Extensions
HINT 1

This problem involves two variables : time and distance. Try to determine which one it is better to focus on.
HINT 2

How much time has Bessie used in getting half way?
SOLUTION

The speed of light might just do! It takes the whole two hours to reach the half-way mark.


EXTENSION

This is not the first time we have come across one of these time-distance problems. Check out Aha! #63 An ill wind .