Answer and Explanation:
The computation is shown below:
a. Â
Particulars          F          G        H
Selling price (a) Â Â Â $100 Â Â Â Â Â Â $80 Â Â Â Â $110
Variable costs (b) Â -$60 Â Â Â Â Â Â -$50 Â Â Â Â Â -$65
Contribution Margin $40 Â Â Â Â Â Â $30 Â Â Â Â Â $45
Milling machine time
(minutes) Â Â Â Â Â Â Â Â Â Â 10 Â Â Â Â Â Â Â 6 Â Â Â Â Â Â Â Â 5
Contribution Margin
per minute        $4        $5        $9
based on the above calculation, the product H should be emphasized as it has the highest contribution margin per minute
b. The price the company should pay is
= $9 × 60 minutes per hour
= $540