Question

To get to the other side of the lake, one can drive around it on Lake Road, go over the bridge or ride the ferry. How many different ways can one go across the lake and back?

5,6,9

Answer 1

The other person is correct it, is 9.

Explanation:

Answer 2

The answer is 9, here are all the possible combinations...

road, road
road, bridge
road, ferry
bridge, bridge
bridge, ferry
bridge, road
ferry, ferry
ferry, bridge
ferry, boat

(or you can do 3 input combinations by 3 output combinations "3 x 3" = 9)

Cheers!