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Finding the Fourth Proportional to 129.40, 178.53 and 82.78

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Solution

The fourth proportional to 129.40, 178.53 and 82.78 is: 114.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.40 : 178.53 = 82.78 : x
  2. Step 2: Convert to fraction form
    129.40/178.53 = 82.78/x
  3. Step 3: Cross multiply
    129.40x = 178.53 × 82.78
  4. Step 4: Simplify right side
    129.40x = 14,778.71
  5. Step 5: Solve for x
    x = 14,778.71/129.40
  6. Step 6: Final answer
    x = 114.21

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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.