Final answer:
To maximize his earnings, the craftsman should make an additional 10 jewelry sets.
Step-by-step explanation:
To maximize his earnings, the craftsman should continue making jewelry sets as long as the decrease in price does not exceed the increase in quantity. Let's calculate the optimal number of sets:
1. The initial price of each set is $500.
2. For each additional set made, the price decreases by $25.
3. Let's assume the craftsman makes x additional sets. The new price per set is:
$500 - $25x.
4. The total revenue from selling 10 sets at $500 each is:
$500 x 10 = $5000.
5. The revenue from selling x additional sets at $500 - $25x each is:
($500 - $25x) x x.
6. To maximize earnings, we need to maximize the revenue. So, the total revenue is:
$5000 + ($500 - $25x) x x.
7. We can expand the expression and simplify it to find the maximum:
$5000 + (500x - 25x^2).
8. To find the maximum, we can take the derivative of the expression and set it equal to 0:
d/dx ($5000 + (500x - 25x^2)) = 0.
9. Solving the equation, we find x = 10.
10. Therefore, the craftsman should make an additional 10 sets to maximize his earnings.