$($Ignore income taxes in this problem.$)$ Czaplinski Corporation is considering a project

that would require an investment of $$323,000$ and would last for $7$ years. The incremental annual

revenues and expenses generated by the project during those $7$ years would be as follows:

The scrap value of the project's assets at the end of the project would be $$22,000.$ The payback

period of the project is closest to $\_\_\_\_\_\_\_\_\_\_\_\_$ years.