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

Explanation:

0.19 m/s and 0.45 m/s

i think the answer is a, hope this : )