Hello. Missed out a sentence which is why the questions looked so weird. So sorry about it.
By right it should be
1. Calculate the NPV of the product.
2. Undertake sensitivity analysis to show by how much the following factors would have to change before the product ceased to be worthwhile: A. The discount rate (Use the method of interpolation with r values of 15% & 20%.) B. Initial outlay of the machinery C. Residual value of the machinery D. Duration