Revenue Payback Period - L3 Management Accounting: Costing Chapter 9

JoBovis

Within my Osborne books, some of the answers which are written give two different payback periods for the same information. The payback period I am familiar with and can calculate with no issues is the payback from the start to the break even point. As per the example 3yrs and 6 months.

However, I have no idea how the following was calculated?
"in terms of revenue, the payback period is 2yrs and 6months" (page 324 9.2 a)

year 0 (0) Cumulative (0)
year 1 (95) Cumulative (95)
year 2 30 Cumulative (65)
year 3 40 Cumulative (25) (25/50)x12=6months
year 4 50 Cumulative 25
year 5 27 Cumulative 52