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Finding the Fourth Proportional to 137.76, 206.40 and 86.24

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Solution

The fourth proportional to 137.76, 206.40 and 86.24 is: 129.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    137.76 : 206.40 = 86.24 : x
  2. Step 2: Convert to fraction form
    137.76/206.40 = 86.24/x
  3. Step 3: Cross multiply
    137.76x = 206.40 × 86.24
  4. Step 4: Simplify right side
    137.76x = 17,799.94
  5. Step 5: Solve for x
    x = 17,799.94/137.76
  6. Step 6: Final answer
    x = 129.21

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.