I also need to see the formula used. Consider four mutually exclusive alternatives:

 $7,500            $5,000            $1,500           $9,000

 Uniform Annual Benefit     $1,700            $1,400            $ 400            $2,500 

Each alternative has a 5-year useful life and no salvage value. Compute the Payback Period (to 2 decimals) for each alternative and determine which alternative should be selected.