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Finding the Fourth Proportional to 138.30, 207.45 and 99.90

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Solution

The fourth proportional to 138.30, 207.45 and 99.90 is: 149.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.30 : 207.45 = 99.90 : x
  2. Step 2: Convert to fraction form
    138.30/207.45 = 99.90/x
  3. Step 3: Cross multiply
    138.30x = 207.45 × 99.90
  4. Step 4: Simplify right side
    138.30x = 20,724.26
  5. Step 5: Solve for x
    x = 20,724.26/138.30
  6. Step 6: Final answer
    x = 149.85

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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.