please refer to the image below and kindly please answer and explanation....

THIS IS ACTUALLY A PRE-CALCULUS SUBJECT ABOUT :

Defining an Ellipse and Determining the Standard Form of Equation of an Ellipse

A spheroid {or oblate spheroidl is the surface obtained by rotating an ellipse around its minor axis. The bowl in Figure 1.41 is in the shape of the lower half of a spheroid; that is. its horizontal cross sections are circles while its vertical cross sections that pass through the center are semiellipses. If this bowl is ID in wide at the opening and #10 in deep at the center, how deep does a circular cover with diameter 9 in go into the bowl? I\" in Figure l .41