Math 8 –
Name
NOTES: Cube Root Applications
Date
Today’s Objectives
 Review how to evaluate cube roots.
 Use cube roots to solve real-world problems.
Review: Michael needs to mow a backyard in the shape of a square. The length of a
diagonal of the backyard is approximately 226.27 ft. Find the following:
a) The length of each side of the backyard.
b) The area of the backyard.
c) The perimeter of the backyard.
Example: Amber is working on a science project for which she needs 350 cubic inches of
sand. She is going to the beach to get the sand she needs, and she is also going to make a
cube out of cardboard to contain the sand. What is the smallest integer length of each
side of a cube that Amber could use to contain her sand?
Practice: During the summer, the city treats its public pool with chlorine twice a week.
The pool is in the shape of a cube, with each side measuring 12 ft. The amount of
chlorine the city puts in the pool for each treatment is equal to 5% of the pool’s total
volume. How much chlorine does the city put in its pool for each treatment?
How much chlorine does the city put in its pool each week?
How much chlorine does the city use for an entire summer? (The city’s pool is open
from Memorial Day through Labor Day -- 14 weeks)
Practice: Three college refrigerators are on sale at the appliance store. All three
have storage areas that are cubes. They have the following internal measurements
and prices. Comparing the cost per cubic foot, which refrigerator is the best buy?
Refrigerator #1
1.5 ft, costs $98
Refrigerator #2
2.1 ft, costs $142
Refrigerator #3
1.75 ft, costs $124