Question

For his phone service Bob pays the monthly fee of $30 and he pays an additional five cents per minute of use. At least he has been charged in a month is $94.70. What are the possible numbers of minutes he has used his phone in a month? Use m for the number of minutes and solve you’re in equality for m.

Answer 1

We can write an expression for the cost of Bob's phone service as follows:

First, remember that five cents are 0.05 dollars.

`C=30+0.05m`

Where C is the cost and m are the minutes.

We know that at least he has been charged in a month is $94.70.

We can express this as an inequality:

`30+0.05m\ge94.70`

To find the possible number of minutes, we have to solve the previous equation for m. This is:

`\begin{gathered} 0.05m\ge94.70-30 \\ 0.05m\ge64.70 \\ m\ge(64.70)/(0.05) \\ m\ge1294 \end{gathered}`

Therefore, the possible numbers of minutes he has used in his phone in a month are:

`m\ge1294`