8.

a. The product to emphasize can be determined by computing the contribution margin per unit of the scarce resource, which in this case is tapping machine time.

 

 

Product E should be emphasized because it has the greatest contribution margin per unit of the scarce resource.

 

b. If additional tapping machine time would be used to produce more of Product E, the time would be worth 60 × $20 = $1,200 per hour.