Radius of a Sphere A jeweler has three small solid spheres made of gold, of radius 2 mm, 3 mm, and 4 mm. He decides to melt these down and make just...

74. Radius of a Sphere A jeweler has three small solid spheres made of gold, of radius 2 mm, 3 mm, and 4 mm. He decides to melt these down and make just one sphere out of them. What will the radius of this larger sphere be? 75. Dimensions of a Box A box with a square base and no top is to be made from a square piece of cardboard by cutting 4-in. Squares from each corner and folding up the sides, as shown in the gure. The box is to hold 100 in3. How big a piece of cardboard is needed?