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Finding the Fourth Proportional to 138.98, 208.54 and 87.65

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Solution

The fourth proportional to 138.98, 208.54 and 87.65 is: 131.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.98 : 208.54 = 87.65 : x
  2. Step 2: Convert to fraction form
    138.98/208.54 = 87.65/x
  3. Step 3: Cross multiply
    138.98x = 208.54 × 87.65
  4. Step 4: Simplify right side
    138.98x = 18,278.38
  5. Step 5: Solve for x
    x = 18,278.38/138.98
  6. Step 6: Final answer
    x = 131.52

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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.