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Finding the Fourth Proportional to 87.28, 120.39 and 52.78

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Solution

The fourth proportional to 87.28, 120.39 and 52.78 is: 72.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.28 : 120.39 = 52.78 : x
  2. Step 2: Convert to fraction form
    87.28/120.39 = 52.78/x
  3. Step 3: Cross multiply
    87.28x = 120.39 × 52.78
  4. Step 4: Simplify right side
    87.28x = 6,354.18
  5. Step 5: Solve for x
    x = 6,354.18/87.28
  6. Step 6: Final answer
    x = 72.80

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.