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Finding the Fourth Proportional to 217.10, 299.40 and 129.72

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Solution

The fourth proportional to 217.10, 299.40 and 129.72 is: 178.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    217.10 : 299.40 = 129.72 : x
  2. Step 2: Convert to fraction form
    217.10/299.40 = 129.72/x
  3. Step 3: Cross multiply
    217.10x = 299.40 × 129.72
  4. Step 4: Simplify right side
    217.10x = 38,838.17
  5. Step 5: Solve for x
    x = 38,838.17/217.10
  6. Step 6: Final answer
    x = 178.90

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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.