The amount of money that Sarah earns varies directly with the number of hours worked. If Sarah earns $320 fir working 40 hours, determine the constant of proportionality.
To find the constant of proportionality, we need to set up a proportion using the information given. We'll set up the proportion using the formula for direct variation: y = kx, where y is the amount of money earned, x is the number of hours worked, and k is the constant of proportionality.
In this case, we can plug in the information given: y = 320 (the amount of money earned) and x = 40 (the number of hours worked):
320 = k * 40
To solve for k, we divide both sides of the equation by 40:
320/40 = k
8 = k
Therefore, the constant of proportionality is 8.