Please explain further the difference here, solutions are in the links, but the way to obtain results is so different that I am not understanding which one is right and which one is not

1. Calculating Payback What is the payback period for the following set of cash flows?

https://www.chegg.com/homework-help/questions-and-answers/year-0-1-2-3-4-cash-flow-7-700-1-900-3-000-2-300-1-700-payback-period-set-cash-flows-given-q86376551

2. Calculating Payback An investment project provides cash inflows of $835 per year for eight years. What is the project payback period if the initial cost is $1,900? What if the initial cost is $3,600? What if it is $7,400?

https://www.chegg.com/homework-help/questions-and-answers/investment-project-provides-cash-inflows-835-per-year-eight-years--project-payback-period--q81490933

\begin{tabular}{cr} Year & Cash Flow \\ \hline 0 & $7,700 \\ 1 & 1,900 \\ 2 & 3,000 \\ 3 & 2,300 \\ 4 & 1,700 \end{tabular}