You buy two rolls of wrapping paper. Each roll has the same lateral surface area. What is the diameter of roll B? Roll A: height:3 length:30. Roll B: height:D Length:24
The area of lateral surface is equal that the perimeter multiply by the length. So the lateral surface area of roll A is 3*π*30=90π. Roll B: d*π*24=24dπ. Put them together: 90π=24dπ. So d=3.75 in.
