Helton Barrels, Inc. (HBI), manufactures oak barrels for the wine industry at its facility in the United States. One of the raw materials used for some of its barrels is French oak lumber. The company fabricates the oak lumber into the appropriate-sized staves and assembles these staves, along with other components, into barrels. In July 2011, the company signed a contract to buy oak lumber from a French supplier for the coming two years. The contract calls for HBI to pay the supplier in euros (€), although all other costs that HBI incurs are paid for in dollars. A summary of the production cost for one barrel, based on the expected production level, follows:
Variable costs:
French oak ............ $100*
All other variable costs ........ 150
Fixed costs ............. 50
*Based on the exchange rate at the time the contract with the French supplier was signed. The cost of lumber in euros was €77.50 as of July 2011.
The exchange rate between the dollar and the euro was $1.43 5 €1.00 in July 2011 when the contract was signed. By July 2012, the exchange rate had changed to $1.23 5 €1.00.

Required
a. CVP analysis is based on several assumptions. Explain which of these assumptions would be violated as a result of HBI having to pay for one of its raw materials in euros while its other costs and revenues are priced in dollars.
b. What effect, if any, would the change in the exchange rate have on HBI’s variable cost per unit for July 2011 versus July 2012?
c. What effect, if any, would the change in the exchange rate have on HBI’s contribution margin per unit for July 2011 versus July 2012?
d. What effect, if any, would the change in the exchange rate have on HBI’s fixed cost per unit for July 2011 versus July 2012?