In particular i have to find the variance of this random variable
$$U = \int_{-\infty}^{y} \frac{1}{\sqrt{2\pi}}e^{-\frac{1}{2}(x-T)^2} dx$$
where T is a ranadom variable distributed with a normal distribution with mean $\mu$ and variance $\sigma^2$.
So i have to find the $Var(U)$. How can i find it?
Probably this is a cumulative function of a standard normal with some modification, but i don't know how i can approach it.