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Finding the Fourth Proportional to 81.29, 121.85 and 58.40

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Solution

The fourth proportional to 81.29, 121.85 and 58.40 is: 87.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.29 : 121.85 = 58.40 : x
  2. Step 2: Convert to fraction form
    81.29/121.85 = 58.40/x
  3. Step 3: Cross multiply
    81.29x = 121.85 × 58.40
  4. Step 4: Simplify right side
    81.29x = 7,115.14
  5. Step 5: Solve for x
    x = 7,115.14/81.29
  6. Step 6: Final answer
    x = 87.53

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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.