2. Opportunity Cost and Ira David and Katie are roommates. They spend most of their time studying for economics classes,
but they leave some time for their 2nd and 3rd favorite activities, coding video games and making
friendship bracelets. It takes David an hour to write 50 lines of code and one hour to make 20
friendship bracelets. It takes Katie an hour to write 60 lines of code and one hour to make 30
friendship bracelets. They each work 3 hours per week.
What is the opportunity cost

For every corresponding pair of cross sections, the area of the cross section of a sphere with radius r is equal to the area of the cross section of a cylinder with radius and height 2r minus the volume of two cones, each with a radius and height of r. a cross section of the sphere is and a cross section of the cylinder minus the cones, taken parallel to the base of cylinder, is the volume of the cylinder with radius r and height 2r is and the volume of each cone with radius r and height r is 1/3 pie r^3. so the volume of the cylinder minus the two cones is therefore, the volume of the cylinder is 4/3pie r^3 by cavalieri's principle. (fill in options are: r/2- r- 2r- an annulus- a circle -1/3pier^3- 2/3pier^3- 4/3pier^3- 5/3pier^3- 2pier^3- 4pier^3)