The weight W of an aluminum flatboat varies directly with the L length of the boat. If a 9-ft boat weighs 162 pounds, then what is the weight of a 8 ft boat?
Well, it does not, but anyway
W = k * L
162 = k * 9
k = 162/9
then
W = k * 8
W = (162/9) 8
W = 144
Problem is, unlike in math class, when you make a boat longer you have to make it stronger and wider and deeper
so in real life it is closer to
W = k * L^3