Inverse Variation Question 4 with Solution Last week, I went over inverse variation, and I gave you four inverse variation problems to try on your own. You can see that post here: Inverse Variation Today I would like to give a solution to the last of those four problems. You can see a solution to the first three problems here: Q1 Q2 Q3 Example: Suppose that z varies directly as x2 and inversely as y3. If z = 9 when x = 3 and y = 2, what is y when z = 4.5 and x = 6 ? Try to solve the problem yourself before checking the solution below. Solution: We are given that z = kx2/y3 for some constant k. Since z = 9 when x = 3 and y = 2, we have 9 = k(3)2/23 = 9k/8. So k = 8, and z = 8x2/y3 . We now substitute z = 4.5 and x = 6 to get 4.5 = 8(6)2/y3 . So y3 = 8(36)/4.5 = 64, and therefore y = 4, choice D. More Problems with Explanations If you are preparing for the SAT, ACT, or an SAT math subject test, you may want to take a look at the Get 800 collection of test prep books. And if you liked this article, please share it with your Facebook friends: Comments comments