Solution
Paragraphs highlighted in green indicate diagrams or tables that can be shared in the “Case exhibits” section.
Paragraphs highlighted in blue can be verbally communicated to the interviewee.
Paragraphs highlighted in orange indicate hints for you how to guide the interviewee through the case.
The following structure provides an overview of the case:

I. Product/Capacity
The interviewee should ask about the following issues:
- Capacity of the machine
- Demand for each kind of product
- Revenue / costs for each product
- Production time for each product
Share Diagram 2 with an overview of the capacity and Table 1 with an overview of the product mix’s demand/profitability if asked.
1. What mix of products should our client produce?
Information to be shared if the interviewee specifically asks for it
- 500 “bag-widths“ produced per hour per product type
- Machine run time:
- 20 hours per day
- 5 days a week
- 50 weeks per year
The interviewee should calculate the total annual profit and production time per product line.
Bags produced per hr
Total annual profit
Production Time

4” bags
# bags produced /hour = 500 x 6 = 3,000
Total annual profit = $0.02 x 9M = $180,000

8” bags
# bags produced /hour = 500 x 3 = 1,500
Total annual profit = $0.03 x 3M = $90,000
12” bags
# bags made /hour = 500 x 2 = 1,000
Total annual profit = $0.04 x 3M = $120,000

Machine run time = 20 hrs/day x 5 days/week x 50 weeks per yr
= 5000 hrs per yr
Share Table 2 with an overview of the solution when the interviewee is finished with the calculation or gets stuck.
Main Conclusion
Under current capacity constraints (5000 hours/year), our client should produce 4” and 8” bags. This product mix generates the highest profit ($270k/year)
II. New Machine
2. Should the client invest in another roller?
Information that can be shared if inquired by the interviewee:
- Cost of new roller = $750,000
- Payback needed = 5 yrs
- The roller will add an additional 5,000 hrs of machine run time
- Mature market, no dramatic changes
- Throughput growing at 2% due to efficiency of new roller
The interviewee should realize that if the new roller is able to meet the currently-unmet demand for 12 bags, our client’s profit would be $600K in 5 years.
Profit over 5 years
= Annual profit from 12" bags * 5 yrs = $120,000 * 5 = $600,000
However, the client must pay for the roller within 5 years. There is a profit shortfall of $150K.
Unrecovered investment
= Profit over 5 yrs - Cost of new roller = $600,000 - $750,000
= $150,000
At the current demand level, 2,000 machine production hours will NOT be used.
Annual unused capacity of new roller
= Machine run time - Capacity needed to meet 12" bags demand
= 5,000 - 3,000 hrs = 2,000 hrs
3. Why might it be a good idea to invest in a new machine?
Possible answers:
- The demand growth rate could exceed 2%
- Since the current market is mature, we could introduce a new product
- We can rent out surplus machine production hours to increase revenue
- Prices must increase to increase revenue
III. New Product
4. If we were to produce a new bag, what annual profit is required in order to justify investing in a new roller?
Situation:
The client’s R&D team has just come out with a new bag. It’s a 2-in-1 bag, one side holds your sandwich and the other side holds your chips or lettuce to keep things from getting soggy. This bag is 6”.
Information to be shared if inquired by the interviewee:
- There is no lag time between production and market acceptance.
- Unrecovered investment from new roller = $150K
- Payback period = 5 years
Additional profit needed

Possible ways to gain $30,000 per year in profit from a new product:
- $0.03 profit per bag at 1M bags
- $0.015 profit per bag at 2M bags
- $0.01 profit per bag at 3M bags
If the interviewee does NOT suggest combinations, ask them to suggest a profit per bag and the corresponding sales volume required.
5. Draw the graph that represents the different profit/quantity combinations that would justify an investment in a new roller. Does this curve have any end points for our client given that the new machine will produce 6” bags @ 4 bags per bag-width for 2000 hours per year?
Share Diagram 3 with the interviewee.
Key Insights
Yes, there are two end points:
- The lower limit of demand depends on price sensitivity. A higher profit margin such as $1 per bag is not feasible as production quantities wouldn’t be worth it.
- The maximum demand we can serve depends on our production capacity. With the new roller, we can produce up to 4M of the new type of bag every year.
Bags made per hr
Unused capacity = 2,000 hrs per year
Maximum production level
IV. Conclusion
At the end of the case, the interviewee should come to the following conclusions:
- The client can best utilize their current capacity by producing 4” and 8” bags on the roller because the combined profitability from this product mix is highest at $270K per year.
- The client should NOT invest in a new bag machine because they cannot pay for the machine within 5 years. (They will still owe $150K.)
- However, investment in a new machine may make sense if we are able to meet the annual demand of 12” bags and find a way to monetize the machine’s surplus capacity.