Question

for the following variables, determine whether r is a function of s, s is a function of r, or neither. r is the amount due on a cell phone bill and s is the number of minutes used. choose the correct answer below. a. s is a function of r. b. neither r nor s are functions of each other. c. both r and s are functions of each other. d. r is a function of s.

Explanation:

Step1: Define function concept

A function is a relation where for each input value, there is exactly one output value.

Step2: Analyze r as a function of s

The amount due on a cell - phone bill ($r$) is determined by the number of minutes used ($s$). Usually, there is a rate (e.g., per - minute rate) and perhaps some fixed charges. For a given number of minutes used ($s$), using the billing formula (e.g., $r = \text{fixed charge}+\text{rate}\times s$), there is exactly one amount due ($r$). So $r$ is a function of $s$.

Step3: Analyze s as a function of r

However, for a given amount due ($r$), there could be multiple combinations of usage (e.g., different plans with different over - usage charges could result in the same bill amount for different numbers of minutes used). So $s$ is not a function of $r$.

Answer:

D. r is a function of s.