I am iOS developer. I made an application for chat which required registration for go into app.
In registration screen, it require DATE OF BIRTH. Apple reject my app for more than 3 times because of DATE OF BIRTH field. I have told them that into our privacy policy we described that user's age must be more than 17 so, we need to add this field for date verification.

But, still they are rejecting my app. 

Please help me.


Question: Find volume of cask
Answer: We place the centre of the cask at the origin, and assume that the cask is symmetrical about its mid-plane. 

Consider the parabola $y=40-kx^2$. At $x=50$ we want $y=30$. So $k=\frac{10}{2500}=\frac{1}{250}$.  

We will rotate this parabola about the $x$-axis. The resulting solid is the cask.

It is useful to integrate from $x=0$ to $x=50$, and double. By the usual formula, the volume, in cubic cm, is
$$2\int_0^{50}\pi\left(40-\frac{x^2}{250}\right)^2\,dx.$$

Remark: Kepler once wrote a little book about how to compute the volumes of Austrian wine casks. The book did not sell well, and Kepler had to go back to casting horoscopes and theorizing about the motions of the planets.