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Finding the Fourth Proportional to 139.20, 207.72 and 115.20

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Solution

The fourth proportional to 139.20, 207.72 and 115.20 is: 171.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.20 : 207.72 = 115.20 : x
  2. Step 2: Convert to fraction form
    139.20/207.72 = 115.20/x
  3. Step 3: Cross multiply
    139.20x = 207.72 × 115.20
  4. Step 4: Simplify right side
    139.20x = 23,929.34
  5. Step 5: Solve for x
    x = 23,929.34/139.20
  6. Step 6: Final answer
    x = 171.91

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.