Test 3 Section 5 - #6 (page 527)

It's pretty rare to see "inversely proportional" on the SAT, but it is fair game. Inversely proportional means:

x₁y₁ = x₂y₂

Contrast that with the more common proportionality you'll see, which is DIRECT proportionality:

x₁/y₁ = x₂/y₂

Basically, what all this means is:

• If two variables are inversely proportional, one will go up as the other goes down.
• If two variables are directly proportional, they both go up at the same time.

If x and y are inversely proportional, then so are x² and y². And if those two are inversely proportional, taking the inverse of ONE of them will create direct proportionality. So 1/x² is directly proportional to y². That's answer choice (E).