A shell-and-tube heat exchanger with one shell and two tube passes is designed to heat liquid water flowing at \(3.0 \mathrm{~kg} / \mathrm{s}\) from 25 to \(65^{\circ} \mathrm{C}\) using hot air. The air enters the shell of the exchanger at \(175^{\circ} \mathrm{C}\), and when the heat exchanger is new, the air exits at \(90^{\circ} \mathrm{C}\). The overall heat transfer coefficient is composed of thermal resistances associated with water flow inside the tubes, conduction through the tube walls, and air flow across the tube bank. Its initial value is \(200 \mathrm{~W} / \mathrm{m}^{2} \cdot \mathrm{K}\). Over time, \(20 \%\) of the tubes develop leaks, and are welded shut during routine maintenance. With the same mass flow rate of water flowing through fewer tubes, would you expect the overall heat transfer coefficient to change significantly? Explain your reasoning. Assuming the overall heat transfer coefficient is unchanged, determine the exit temperature of the water when operating with only \(80 \%\) of the tubes active.