math
posted by summer on .
Can someone please explain this problem to me: I have to use integrals to find volumes with known cross sections but i just don't understand. I have to do a lot of examples for homework like this so can someone show me so I can do my other problems? Thanks!
Consider a solid bounded by y=2ln(x) and y=0.9((x1)^3). If cross sections taken perpendicular to the xaxis are isosceles right triangles with the hypotenuse in the base, find the volume of this solid.

Kevin showed a set of counters with all the counters red. What fraction of Kevin's set was red if he had 5 counters? What if he had 3 counters? Explain.