Question

Janelle is planning to knit scarves to give to her friends and family members on Valentine's day. She will need to purchase 200 yards of yarn for each scarf that she is going to knit. The function Y(s) represents the amount of yarn Janelle will need, in yards, in order to knit s scarves.
What is the domain of Y(s)?

Answer 1

Since she can only make whole scarves and can't make a negative number, the domain is the nonnegative integers:
s ∈ {0, 1, 2, 3, …}.
(If fractional scarves were allowed, the domain would be all real numbers s ≥ 0, but here s must be an integer.)