Question 1208389
<pre>
Here is everthing you need:

The water in the bottom of the hemispheric bowl is a spherical cap, and the
formula for its volume is

Volume of a spherical cap = {{{expr(1/3)*pi*h^2(3R - h)}}}, where h=9 cm. is the
height of the spherical cap (water), and radius R = 21 cm. (half the 42 cm
diameter at the top).

Volume of a sphere is {{{expr(4/3)*pi*R^3}}}, where R = 21 cm. 

This is a hemisphere, not a whole sphere, so remember that the volume of a
hemisphere is only 1/2 the volume of a whole sphere.

So you only need to calculate those two volumes and subtract them to find the
volume to be filled between the top of the water and the top of the bowl.

Your answer will be in cubic centimeters. Then you can use the fact that 
1 cubic centimeter of water is exactly 1 milliliter of water.  Then to 
convert from milliliters to liters, you will multiply by 1000.  

Edwin</pre>