Unit 5, Lesson 19

Estimating a Hemisphere

Grade 8

Practice

1. Problem 1

   Student Task Statement

   A baseball fits snugly inside a transparent display cube. The length of an edge of the cube is 2.9 inches.

   Is the baseball’s volume greater than, less than, or equal to cubic inches? Explain how you know.

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2. Problem 2

   Student Task Statement

   A hemisphere fits snugly inside a cylinder with a radius of 6 cm. A cone fits snugly inside the same hemisphere.

   1. What is the volume of the cylinder?
   2. What is the volume of the cone?
   3. Estimate the volume of the hemisphere by calculating the average of the volumes of the cylinder and cone.

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3. Problem 3

   Student Task Statement

   1. Find the hemisphere’s diameter if its radius is 6 cm.

   2. Find the hemisphere’s diameter if its radius is m.

   3. Find the hemisphere’s diameter if its radius is 9.008 ft.

   4. Find the hemisphere’s radius if its diameter is 6 cm.

   5. Find the hemisphere’s radius if its diameter is m.

   6. Find the hemisphere’s radius if its diameter is 9.008 ft.

4. Problem 4

   ForLesson 9: Linear Models

   Student Task Statement

   After almost running out of space on her phone, Elena checks with a couple of friends who have the same phone to see how many pictures they have on their phones and how much memory they take up. The results are shown in the table.

   number of photos	2,523	3,148	1,875
   memory used (MB)	8,072	10,106	6,037

   1. Could this information be reasonably modeled with a linear function? Explain your reasoning.

   2. Elena needs to delete photos to create 1,200 MB of space. Estimate the number of photos she should delete.