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Finding the Fourth Proportional to 139.20, 207.78 and 129.60

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Solution

The fourth proportional to 139.20, 207.78 and 129.60 is: 193.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.20 : 207.78 = 129.60 : x
  2. Step 2: Convert to fraction form
    139.20/207.78 = 129.60/x
  3. Step 3: Cross multiply
    139.20x = 207.78 × 129.60
  4. Step 4: Simplify right side
    139.20x = 26,928.29
  5. Step 5: Solve for x
    x = 26,928.29/139.20
  6. Step 6: Final answer
    x = 193.45

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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.