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Finding the Fourth Proportional to 86.59, 129.10 and 81.43

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Solution

The fourth proportional to 86.59, 129.10 and 81.43 is: 121.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.59 : 129.10 = 81.43 : x
  2. Step 2: Convert to fraction form
    86.59/129.10 = 81.43/x
  3. Step 3: Cross multiply
    86.59x = 129.10 × 81.43
  4. Step 4: Simplify right side
    86.59x = 10,512.61
  5. Step 5: Solve for x
    x = 10,512.61/86.59
  6. Step 6: Final answer
    x = 121.41

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.