A package of paper towels contains 3 rolls. Each package of paper towels costs $2.79.

A function, f (x), is written to represent the cost of purchasing x packages of paper towels.

What is the practical domain for the function f (x) ?

(a) all whole numbers that are multiples of 3

(b) all positive integers

(c) all real numbers

(d) all whole numbers

Answer: (b) all positive integers

Step-by-step explanation:

We know that the domain of a function is the set of all values for x (independent variable) for which the function must be defined.

Given: A package of paper towels contains 3 rolls. Each package of paper towels costs $2.79.

A function, f (x), is written to represent the cost of purchasing x packages of paper towels.

i. e. the number of towels must be a positive integer.

Hence, the practical domain for the function f (x) must be all positive integers.

Answer: b. All positive integers