Net and Present Value

Mar 2013
4
0
Wales
Hi Maths Help Forum

YearOutInDiscountNetPresent Value
0£247,3321-£247,332-£247,332
1£25,0000.8772£25,000£21930
2£25,0000.7695£25,000£19237.50
3£30,0000.675£30,000£20250
4£30,0000.5921£30,000£17763
5£35,0000.5194£35,000£18179
6£35,0000.4556£35,000£15946
7£40,0000.3996£40,000£15984
8£40,0000.3506£40,000£14024
9£45,0000.3075£45,000£13837.50
10£45,0000.2697£45,000£12136.50

From the above table (is this complete?) how would you work out the payback period in years?