Rowing to Shore and Then Running Away

time

0

set time to 0 to change v or solution

v

4

solution

1

2

axes

show strategy

L

is in a rowboat in the center of a circular lake (black dot).

L

has to escape from

M

(red dot), who knows

L

must come ashore. Although

L

can run faster than

M

once on land,

M

runs

v

times faster than

L

can row, where

3≤v≤5

. Is there a strategy for

L

to escape?

Richard F. Guy shows that

L

can always escape when

M

runs at most 4.6 times as fast as

L

rows (solution 2).

[1] M. Gardner, The Colossal Book of Short Puzzles and Problems, New York: W. W. Norton, 2006 pp. 237, 256–257.

Izidor Hafner