A graduated cylinder contains water to the 15-cm'level. A stone was placed in the
water, which rose to the 21-cm level. Then a cork stopper, with the same stone resting
on it so as to hold both submerged, was placed in the water. The water rose to the 26-
cmº level. What was the volume of the cork stopper, in cm"?
11
6
26
5
21