Thread: Simple speed/length/time question (Urgent)

Okey, person A swims across a lake at 3km/h, where person B jogs around. Person A use the same time as Person B to swim across of the lake as Person B runs around it one time.

What's the speed of Person B?

To long since I've done this stuff so stuck atm... Any help would be greatly appriciated!

Could it be

person A swims in (2*r/3)hrs.

so,speed of person B=(2*pi*r*3/2*r)km/h.
=3*pi km/h.