Question

A forest is in the shape of a rectangle 5 miles long and 3 miles wide. The density of the trees at a distance of x miles form the 5 mile side is given by p(x) trees per square mile. Which expression gives the number of trees in the forest?

A. integral from 0-3 p(x) dx
B.3 Integral from 0-3 p(x) dx
c.5 Integral from 0-3 p(x) dx
D. 3 Integral from 0-3 p'(x) dx
E.5 Integral from 0-3 p'(x) dx

Help please!

Answer 1

The expression would be:
\[N=\int\limits_{x=0}^{x=3}\int\limits_{y=0}^{y=5}\rho(x)dxdy=5\int\limits_{x=0}^{x=3}\rho(x)dx\]