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Finding the Fourth Proportional to 129.87, 194.78 and 72.15

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Solution

The fourth proportional to 129.87, 194.78 and 72.15 is: 108.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.87 : 194.78 = 72.15 : x
  2. Step 2: Convert to fraction form
    129.87/194.78 = 72.15/x
  3. Step 3: Cross multiply
    129.87x = 194.78 × 72.15
  4. Step 4: Simplify right side
    129.87x = 14,053.02
  5. Step 5: Solve for x
    x = 14,053.02/129.87
  6. Step 6: Final answer
    x = 108.21

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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.