If h1 and h2 are the difference in levels between the ground surface and the formation levels at the two sections and ‘n’ is the side slope and ‘D’ is the distance between them, the prismoidal correction for a level section is
1
\(\rm +\frac{D_n}{3}(h_1-h_2)^2\)
2
\(\rm +\frac{D_n}{6}(h_1-h_2)^2\)
3
\(\rm -\frac{D_n}{6}(h_1-h_2)^2\)
4
\(\rm -\frac{D_n}{6}(h_1+h_2)^2\)