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Finding the Fourth Proportional to 129.80, 178.13 and 128.86

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Solution

The fourth proportional to 129.80, 178.13 and 128.86 is: 176.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.80 : 178.13 = 128.86 : x
  2. Step 2: Convert to fraction form
    129.80/178.13 = 128.86/x
  3. Step 3: Cross multiply
    129.80x = 178.13 × 128.86
  4. Step 4: Simplify right side
    129.80x = 22,953.71
  5. Step 5: Solve for x
    x = 22,953.71/129.80
  6. Step 6: Final answer
    x = 176.84

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.