This Instructional Activity is a part of the Lesson 16, Unit 5, Grade 8. The purpose of this activity is for students to calculate the radius of the cone given the volume and height. This activity is similar to an activity in a previous lesson where students calculated the radius of a cylinder given the volume and height. A difference here is that solving for the unknown takes an additional step to deal with the 1/3. Encourage students to connect the strategies that they used in the warm-up to this problem.