Question

For his phone service, Shen pays a monthly fee of $16,and he pays an additional $0.05 per minute of use. The least he has been charged in a month is $73.45 . 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

Since Shen pays $0.05 per minute and $16 each month, the cost is given by

`0.05m+16`

where m denotes the number of minutes. Since the least he has been charged is $73.45, we can write

`73.45\le0.05m+16`

and we need to find m from this inequality. Then, by subtracting 16 to both sides, we have

`57.45\le0.05m`

and by dividing both sides by 0.05, we get

`\begin{gathered} (57.45)/(0.05)\le m \\ or\text{ equivalently,} \\ m\ge(57.45)/(0.05) \end{gathered}`

Then, we have

`m\ge1149`

What are the possible numbers of minutes he has used his phone in a month? Answer: at least 1149 minutes