A rectangular lake is $150 \mathrm{km}$ long and $3 \mathrm{km}$ wide. The vertical cross-section through the lake in Figure 8.14 shows that the lake is $0.2 \mathrm{km}$ deep at the center. (These are the approximate dimensions of Lake Mead, the largest reservoir in the US, which provides water to California, Nevada, and Arizona.) Set up and evaluate a definite integral giving the total volume of the lake. (FIGURE CAN'T COPY)