Final answer:
To find the constant of proportionality, divide the height of the stack by the number of cases. To find the height of a stack with a different number of cases, multiply the constant of proportionality by the number of cases.
Step-by-step explanation:
To find the constant of proportionality, we need to compare the height of the stack of DVD cases to the number of cases in the stack. Let's assume that the height of the stack of 7 cases is h units. So, in this case, the height to number of cases ratio is h/7. To find the constant of proportionality, we need to divide the height of the stack by the number of cases: h/7 = c, where c is the constant of proportionality.
To find the height of a stack of 12 cases, we can use the constant of proportionality. Since we know the constant is c, and we have 12 cases, the height of the stack can be calculated as: height = c * number of cases = c * 12. Substitute the value of c to get the actual height.