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Finding the Fourth Proportional to 823.20, 1,235.36 and 438.72

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Solution

The fourth proportional to 823.20, 1,235.36 and 438.72 is: 658.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    823.20 : 1,235.36 = 438.72 : x
  2. Step 2: Convert to fraction form
    823.20/1,235.36 = 438.72/x
  3. Step 3: Cross multiply
    823.20x = 1,235.36 × 438.72
  4. Step 4: Simplify right side
    823.20x = 541,977.14
  5. Step 5: Solve for x
    x = 541,977.14/823.20
  6. Step 6: Final answer
    x = 658.38

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.