Answer:
a. Product X = 3.50 years
Product Y = 3.25 years
b. Product Y
Step-by-step explanation:
The cash flows for the two products as well as the balance at the end of each year is given as follows:

For both products, the payback period is reached between the third and fourth year.
Product X:

Product Y:

Under the payback method, the alternative that presents the shortest payback period should be selected. Therefore, Product Y should be selected.