Estimate the volume of the solid that lies below the surface

z=xy and above the rectangle R − hsx, yd | 0 < x < 6, 0 < y < 4j

Use a Riemann sum with m − 3, n − 2, and take the

sample point to be the upper right corner of each square.

(b) Use the Midpoint Rule to estimate the volume of the solid

in part (a).