Directions: Choose the best answer from the four choices given. You may use scratch paper.
The variables x and y are directly proportional, and y = 2 when x = 3. What is the value of y when x = 9?
Choice (B) is correct. Since the variable x and y are directly proportional, they are related by an equation y = kx, where k is a constant. It is given that y = 2 when x = 3, and so 2 = k(3), which gives k = 2/3. Therefore, y = 2/3x, and so when x = 9, the value of y is y = 2/3(9) = 6.