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Finding the Fourth Proportional to 138.71, 208.05 and 87.66

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Solution

The fourth proportional to 138.71, 208.05 and 87.66 is: 131.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.71 : 208.05 = 87.66 : x
  2. Step 2: Convert to fraction form
    138.71/208.05 = 87.66/x
  3. Step 3: Cross multiply
    138.71x = 208.05 × 87.66
  4. Step 4: Simplify right side
    138.71x = 18,237.66
  5. Step 5: Solve for x
    x = 18,237.66/138.71
  6. Step 6: Final answer
    x = 131.49

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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.