A hollow plastic ball floats in a tub of jello (the flavor is irrelevant, but I’ll tell you: it’s key lime). The jello sets, and when the ball is removed, the saucer-shaped depression in the jello measures 6cm across and 1cm deep. If the density of the plastic is twice that of jello, what is the average thickness of the plastic shell?

Thanks for the great solution.

I could point out that the radius of the sphere could have been obtained by the intersection chord property, namely if two chords of a circle intersect, then l1*l2=l3*l4, where l1+l2=length of the first chord, and l3+l4 the second.
In this case, l1=3, l2=3, l3=1, therefore
l4=3*3/1=9
Thus the diameter is 9+1 cm, therefore radius=5 cm.

Best regards and keep up the good work.

Posted by P C on 2004-02-04 20:51:39