The volume formula of a cone is 
the r is the radius and h is the height. However, if you multiply by pi, you will get an approximated volume of the cone. So we will multiply like this for now. 
Don't worry, we'll use pi in the end.
I'm going to assume that 7 inches is your radius. We need to plug in 7 for r and 4 in for h into the equation. Once we do that, it will look like this.
means we will need to divide one by 3. That gives us 0.33333... now we have to multiply by 
we get 16.33333... now the last thing we need to do is multiply by 4, which is h. We get 65.33333. Add pi and you have your answer. 
I'm going to assume that 7 inches is your radius. We need to plug in 7 for r and 4 in for h into the equation. Once we do that, it will look like this.