complete this problem in Excel using NPV and IRR functions. Sentry Company is contemplating the purchase of a new high-speed grinder to replace the existing grinder. The existing grinder was purchased 2 years ago at an installed cost of $60,000; it is being depreciated under MACRS using a 5-year recovery period. The existing grinder is expected to have a usable life of 5 more years (hint: start depreciation expense in year 3 since the existing grinder was purchased two years ago.) The new grinder costs $105,000 and requires $5,000 of installation costs; it has a 5-year usable life and would be depreciated under MACRS using a 5-year recovery period. The