Question

Part IV: Suppose you anticipate needing to call the UK for a 250 minutes and France for 100 minutes. Will a $75 card cover the cost of this much calling? Explain your answer.

Answer 1

$\begin{gathered} \text{ Part I} \\ \text{ Total call for UK} \\ U(x)=0.23x \\ \text{ Total call for France} \\ F(y)=0.21y \end{gathered}$$\begin{gathered} \text{Part II} \\ 0.23x+0.21y\le75 \end{gathered}$$\begin{gathered} \text{ Part IV} \\ \text{ Using the inequality we have for Part II, substitute the following} \\ x=250 \\ y=100 \\ 0.23x+0.21y\le75 \\ 0.23(250)+0.21(100)\le75 \\ 57.5+21\le75 \\ 78.5\le75,\text{ this is invalid since 78.5 > 75} \\ \text{ Therefore, the \ 75 card will not be able to cover the cost of the calling since} \\ \text{ 78.5 is greater than \ 75} \end{gathered}$