DAY 37

Comment

Lisa walked faster than Larry because she walked a greater distance in less time.
Liam also walked faster than Larry because though he took slightly more time he also walked much further.
So Larry was slowest, but who was fastest - Lisa or Larry?

Answer

Lisa walked fastest.

Readers' methods

Bernice Harris, Ohio, USA:
Imagine straight lines from the origin to each person's dot on the graph.
Lisa's line is steepest, which means she was fastest.

Senthil Kumar, Hyderabad, India:
Find the slope of each of the straight lines joining the origin to the given points.
The person coresponding to the largest slope has walked the fastest... here it is Lisa.

Lorna G, aged 16:
Lisa has a large distance and a small time, and although Liam has a larger distance, he has a much larger time. The proportion of distance added on to Lisa's is smaller than the proportion of time added on, and, assuming the scales on the axes would be the same, it almost looks as if he has a 1:1 ratio. This means that Lisa still has a much larger ratio, and so completes her journey the fastest.