# int_2^3 x^2 dx
N <- 1000000
X <- runif(N, 2, 3)
f.of.X <- (3-2)*X^2
mean(f.of.X)


# int_2^2 cos(x)^7 dx
N <- 1000000
X <- runif(N, 2, 3)
f.of.X <- (3-2)*cos(X)^7
mean(f.of.X)