the reflections are modeled by the equation y = 1/4p( x - h )2 + K

if the width of the dish if 4m and the depth is 0.4m where is the focus?

Just do the algebra to get the equation in the form y=ax^2+bx+c, and then use the definition of the focus. It's coordinates are:

\( \frac{-b}{2a} , c-\frac{b^2+1}{4a} \)

Can you do that?

Thanks for your help I figured it out