Directly Proportional vs. Inversely Proportional

Bigb14
Mon, 29 Dec 2008 17:14:36 +0000

I always mess these problems up on the math section…

For example, if a problem says: If height is directly proportional to length, and a piece of board is w long and x high, what is the height of a piece of board that is y long?

When it says directly proportional, I always think the setup is (w)(x)=(y)(z)

However, it’s actually: (w)/(x)=(y)/(z)

Same problem with inverse proportions

Is there a way to straighten this problem out? To me, it’s really hard to remember, because when you say inverse, you think of dividing, when you are actually multiplying. How do you remember this rule? (because it’s driving me insane :P)