$$
\begin{array}{l}{\text { Pressure and Depth At the surface of the ocean the water }} \\ {\text { pressure is the same as the air pressure above the water, }} \\ {15 \mathrm{lb} / \mathrm{in}^{2} \text { . Below the surface the water pressure increases by }} \\ {4.34 \mathrm{lb} / \mathrm{in}^{2} \text { for every } 10 \mathrm{ft} \text { of descent. }} \\ {\text { (a) Find an equation for the relationship between pressure }} \\ {\text { and depth below the ocean surface. }} \\ {\text { (b) Sketch a graph of this linear equation. }} \\ {\text { (b) What do the slope and } y \text { -intercept of the graph }} \\ {\text { represent? }} \\ {\text { (d) At what depth is the pressure } 100 \text { lb/in }^{2} ?}\end{array}
$$