\text { 3. Please prepare a plot of } \frac{(Z-1)}{P} \text { as a function of } P \text { for steam at } 500^{\circ} C \text { on the range of } P=1 M P a \text { to } 5 \text { MPa. Via graphical integration, please determine the value of } \Delta\left[\bar{g}^{R} / \bar{R} T\right] \text { in } M P a / M P a \text {. }