Question

My company charges 10 cents per minute over 5 minutes when using Internet at its store. It also charges a 5 dollar fee for usage. How many minutes can I get with 10 dollars?

Answer 1

so if you use it for less than 5 minutes is more than likely free.

now, you start downloading the macarena song and other mp3s, and it takes longer then they charge 10 cents or $0.10 per minute after those 5 minutes.

so, if you use it

6 mins you pay 1 * 0.10
7 mins you pay 2 * 0.10
8 mins you pay 3 * 0.10
9 mins you pay 4 * 0.10
10 mins you pay 5 * 0.10

x mins you pay (x - 5) * 0.10 so long "x" is 5 or higher.

now, they charge a $5 fee, that's just a connection fee, so is charged only once,

so the cost function will be


`\bf \stackrel{cost}{y}=\stackrel{\textit{connection fee}}{5}+\stackrel{\textit{over 5 mins fee}}{(x-5)0.10} \\\\\\ \textit{how much can you get for 10 bucks? well if 10 bucks is the \underline{cost}} \\\\\\ 10=5+(x-5)0.1\implies 5=0.1(x-5)\implies \cfrac{5}{0.1}=x-5 \\\\\\ 50=x-5\implies \stackrel{minutes}{55}=x`