Inequality Word Problem

Quote:

Originally Posted by OzzMan

A rectangular PV (photovoltaic) solar panel is designed to be $1.42\; m$ long and supply $130\; \frac{W}{m^2}$ of power. What must the width of the panel be in order to supply between $100\; W$ and $150\; W$ ?

Let the width of the panel be x metres. Then:

Power supply $= (130 \, W/m^2) (1.42 x \, m^2) = (130)(1.42 x) \, W = 184.6x \, W$

You therefore require:

$100 \leq 184.6 x \leq 150 \Rightarrow \frac{100}{184.6} \leq x \leq \frac{150}{184.6} \Rightarrow .... \leq x \leq ....$