Average Value of a Function

$\int_{0}^{40} x^2\,dx$

$\frac{1}{2} \int_{0}^{40} x^2\,dx$

$\frac{1}{40} \int_{0}^{40} x\,dx$

$\frac{1}{40} \int_{0}^{40} x^2\,dx$