Question

For his phone service, Chau pays a monthly fee of $20, and he pays an additional $0.07 per minute of use. The least he has been charged in a month is $97.49. What are the possible numbers of minutes he has used his phone in a month? Use m for the number of minutes, and solve your inequality for m.

Answer 1

Step 1: Concept

Given data

Monthly fee = $20

Additional cost per minute = $0.07

Let number of minutes = m

Step 2: Write an inequality equation that will represent the least cost in a month.

In mathematics, the word 'least' represents greater than or equal to.

`\text{Least represent = }\ge\text{ (greater than or equal to)}`

Step 3: Write an inequality equation.

For the least cos t of $97.49 per month.

`\begin{gathered} 0,07m\text{ + 20 }\ge\text{ 97.49} \\ \text{Collect similar terms} \\ 0.07m\text{ = 97.49 - 20} \\ 0.07m\text{ }\ge77.49 \\ \text{Divide both sides by 0.07} \\ (0.07m)/(0.07)\text{ }\ge\text{ }(77.49)/(0.07) \\ \text{m }\ge\text{ 1107} \end{gathered}`

Step 4: Final answer

The possible number of minutes is

`m\text{ }\ge\text{ 1107 minutes}`