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Finding the Fourth Proportional to 129.91, 194.80 and 56.78

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Solution

The fourth proportional to 129.91, 194.80 and 56.78 is: 85.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.91 : 194.80 = 56.78 : x
  2. Step 2: Convert to fraction form
    129.91/194.80 = 56.78/x
  3. Step 3: Cross multiply
    129.91x = 194.80 × 56.78
  4. Step 4: Simplify right side
    129.91x = 11,060.74
  5. Step 5: Solve for x
    x = 11,060.74/129.91
  6. Step 6: Final answer
    x = 85.14

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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.