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Finding the Fourth Proportional to 129.20, 178.30 and 79.45

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Solution

The fourth proportional to 129.20, 178.30 and 79.45 is: 109.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.20 : 178.30 = 79.45 : x
  2. Step 2: Convert to fraction form
    129.20/178.30 = 79.45/x
  3. Step 3: Cross multiply
    129.20x = 178.30 × 79.45
  4. Step 4: Simplify right side
    129.20x = 14,165.59
  5. Step 5: Solve for x
    x = 14,165.59/129.20
  6. Step 6: Final answer
    x = 109.65

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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.