An independent dirt contractor is trying to determine which size dump truck to buy. The contractor knows that as the bed size increases, the net income increases, but he is uncertain whether the incremental expenditure required for the larger trucks is justified. The cash flows associated with cach size truck are estimated below. The contractor's MARR is 18% per year, and all trucks are expected to have a useful life of 5 years. (a) Determine which size truck should be purchased. (b) If two trucks of different size are to be purchased, what should be the size of the second truck