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

$\begin{gathered} \frac{57.45}{0.05}\le m \\ or\text{ equivalently,} \\ m\ge\frac{57.45}{0.05} \end{gathered}$

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