$1\mathrm{.}4.$ A reliable sales forecast has been obtained indicating that the Special Products Company $($see Section $1\mathrm{.}2)$ would be able to sell $30,000$ iWatches, which appears to be enough to justify introducing this new product. However, management is concerned that this conclusion might change if more accurate estimates were available for the research$-$and$-$development cost, the marginal production cost, and the unit revenue. Therefore, before a final decision is made, management wants what$-$if analysis done on these estimates.

Use the spreadsheet from Figure $1\mathrm{.}3($see this chapter's Excel files$)$ and trial$-$and$-$error to perform what$-$if analysis by independently investigating each of the following questions.

a$.$ How large can the research$-$and$-$development cost be before the watches cease to be profitable?

b$.$ How large can the marginal production cost be before the watches cease to be profitable?

c$.$ How small can the unit revenue be before the watches cease to be profitable?