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Finding the Fourth Proportional to 129.21, 178.32 and 76.77

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Solution

The fourth proportional to 129.21, 178.32 and 76.77 is: 105.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.21 : 178.32 = 76.77 : x
  2. Step 2: Convert to fraction form
    129.21/178.32 = 76.77/x
  3. Step 3: Cross multiply
    129.21x = 178.32 × 76.77
  4. Step 4: Simplify right side
    129.21x = 13,689.91
  5. Step 5: Solve for x
    x = 13,689.91/129.21
  6. Step 6: Final answer
    x = 105.95

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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.