Hot oil entering a heat exchanger is to be cooled by water. The overall heat transfer coefficient $U_{av}$ is $200Bt\frac{u}{h}rf{t}^2*F.$ When the exchanger is operated in counter$-$current flow, the following information is available:

$\backslash$table$[[$Material$,\backslash$table$[[$Mass flow$],[$rate$],[(l\frac{b_m}{h}r)$