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Finding the Fourth Proportional to 129.61, 178.71 and 106.21

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Solution

The fourth proportional to 129.61, 178.71 and 106.21 is: 146.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.61 : 178.71 = 106.21 : x
  2. Step 2: Convert to fraction form
    129.61/178.71 = 106.21/x
  3. Step 3: Cross multiply
    129.61x = 178.71 × 106.21
  4. Step 4: Simplify right side
    129.61x = 18,980.79
  5. Step 5: Solve for x
    x = 18,980.79/129.61
  6. Step 6: Final answer
    x = 146.45

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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.