Alvin wants to know what his average paddling rate was for a canoe trip to a campsite. On the way there it took him 7 hours against a river current of 4 km/ hr. On the way back, the same distance took him 5 hours with the same 4 km/hr current.
Let
r
r
= Alvin's average paddling rate. Express the rates against the current and with the current in terms of
r
r
to complete the below table.
Distance Rate Time
Against the current
d
d

With the current
d
d

Using the information summarized in the above table, set up an equation to solve for Alvin's average paddling rate
r
r
.

Alvin's average paddling rate was km/hour (If needed, round to 2 decimal places).