The distance "d" you bike varies directly with the amount of time "t" you bike. Suppose you bike 13.2 miles in 1.25 hours. What is an equation that relates "d" and "t"? What is the graph of the equation? ... ?

The distance "d" you bike varies directly with the amount of time "t" you bike. Therefore,

d α t

To turn it into equality, we introduce k, proportionality constant.

d = kt

We find the value of k from the given conditions. Suppose you bike 13.2 miles in 1.25 hours.

13.2 = k (1.25)

k = 10.8 miles/our

Therefore the equation would be:

d = 10.8t

It is a linear graph with slope 10.8 and it passes at the origin.