Math Problem Statement

A right rectangular prism has edge lengths of 3 1/2 ft, 2 1/4 ft, and 4 1/3 ft. Safara wants to completely fill the prism with identical cubes. The cubes must have edge lengths that are unit fractions. What is the greatest edge length of the cubes that Safara could use? Explain.

Solution

The problem asks to find the greatest edge length of cubes that Safara could use to fill a rectangular prism with given edge lengths of 312ft,214ft,and413ft3\frac{1}{2} \, \text{ft}, 2\frac{1}{4} \, \text{ft}, \text{and} 4\frac{1}{3} \, \text{ft}. The cubes must have edge lengths that are unit fractions.

Step-by-Step Solution:

  1. Convert the mixed numbers into improper fractions:

    • 3123\frac{1}{2} becomes 72\frac{7}{2}.
    • 2142\frac{1}{4} becomes 94\frac{9}{4}.
    • 4134\frac{1}{3} becomes 133\frac{13}{3}.
  2. Find the greatest common divisor (GCD): To determine the largest cube that can completely fill the prism, we need to find the greatest common divisor of these fractions' denominators. To do this, we will:

    • Find the GCD of the denominators 2, 4, and 3, which is 1 (because they have no common factor larger than 1).
  3. The greatest edge length of the cube: Since the GCD of the denominators is 1, the largest cube that can fill the prism without leaving gaps must have an edge length of 112ft\frac{1}{12} \, \text{ft} (which is the least common multiple (LCM) of 2, 4, and 3 for the numerators to form unit cubes).

Thus, the greatest edge length of the cubes Safara could use is 1/12 feet.


Do you want further details or have any questions?

Here are 5 related questions:

  1. How do you find the LCM of fractions in a general case?
  2. How do you calculate the volume of a cube given its edge length?
  3. Can you explain how cube volume relates to prism volume in this scenario?
  4. What happens if the cube's edge length is not a unit fraction?
  5. How do improper fractions help in simplifying such problems?

Tip: Always convert mixed numbers into improper fractions for easier calculation when comparing or simplifying.

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Math Problem Analysis

Mathematical Concepts

Fractions
Greatest Common Divisor (GCD)
Least Common Multiple (LCM)
Volume

Formulas

GCD of fractions
LCM of denominators

Theorems

Greatest common divisor theorem
Least common multiple theorem

Suitable Grade Level

Grades 6-8