Question: Zales Jewelers uses rubies and sapphires to produce two types of rings. A type 1 ring requires 2 rubies, 3 sapphires, and 1 hour of jeweler^'s labor. A type 2 ring requires 3 rubies, 2 sapphires, and 2 hours of jeweler^'s labor. Each type 1 ring sells for $400, and each type 2 ring sells for $500. All rings produced by Zales can be sold. At present, Zales has 100 rubies, 120 sapphires, and 70 hours of jeweler^'s labor. Extra rubies can be purchased at $100 per ruby. Market demand requires that the company produce at least 20 type 1 rings and at least 25 type 2 rings. To maximize profit, Zales should solve the following LP:

X1 = number of type 1 rings produced

X2 = number of type 2 rings produces

R = number of rubies purchased

Solve this LP, and use the output to answer the following:

a. Suppose that instead of $100, each ruby costs $190. Would Zales still

purchase rubies? What would the new optimal solution to the problem be?

b. Suppose that Zales were only required to produce at least 23 type 2 rings.

What would Zale^'s profit be now?

c. What is the most that Zales would be willing to pay for another hour of jeweler^'s labor?

d. What is the most that Zales would be willing to pay for another sapphire?

Please enter the answer to part c.