A swimmer heading directly through a 200m wide river reaches the opposite shore in 6 min 40s. She is washed downstream 480 m. How fast can you swim in calm water?

Answer : v=480m400s=1.2ms

2002+4802=H2

The hypotenuse H=520m

A quicker way to get the length of the hypotenuse is to recognize that this is a simple 5-12-13 triangle where the sides are multiples of 5, 12, and 13:

5 (40) = 200m, 12 (40) = 480m, 13 (40) = 520m

We know that the swimmer travelled 520 m in 400 seconds, so her average speed was:

VR=520m400sec = 1.3ms

hope i got it right! xx