The amount of money that Sarah earns varies with the number of hours worked. If she earns $320 for working 40 hours, determine the constant of proportionality. A. 9 B. 8 C. 7 D. 6

1 answer

We can solve this problem 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.

We are given that Sarah earns $320 for working 40 hours. So we can substitute these values into the formula:

\[320 = k \cdot 40\]

Dividing both sides of the equation by 40 gives:

\[8 = k\]

So the constant of proportionality is 8.

Therefore, the correct answer is B. 8.