This is a problem that can be solved using algebraic substitution. If we define A and B to be the speeds of the two walkers in mph then we know that one of them is 0.5 mph faster than the other. The order here doesn't matter but we'll define B as A + 0.5. Additionally we know that distance = speed times time therefore the two speeds of the hikers combined multiplied by the time (t) must give 11 miles as that is the circumference of the lake: At + Bt = 11 (2)
As we know the relation between A and B is: B = A + 0.5 we can say
At + (A + 0.5)t = 11
2At + 0.5t = 11
we know that t is 2 hours so:
2*2A + 0.5*2 = 11
4A + 1= 11
A = 2.5
as B = A + 0.5 then B = 3
