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Finding the Fourth Proportional to 138.45, 207.68 and 45.90

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Solution

The fourth proportional to 138.45, 207.68 and 45.90 is: 68.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.45 : 207.68 = 45.90 : x
  2. Step 2: Convert to fraction form
    138.45/207.68 = 45.90/x
  3. Step 3: Cross multiply
    138.45x = 207.68 × 45.90
  4. Step 4: Simplify right side
    138.45x = 9,533.25
  5. Step 5: Solve for x
    x = 9,533.25/138.45
  6. Step 6: Final answer
    x = 68.86

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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.