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Finding the Fourth Proportional to 138.88, 208.07 and 87.40

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Solution

The fourth proportional to 138.88, 208.07 and 87.40 is: 130.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.88 : 208.07 = 87.40 : x
  2. Step 2: Convert to fraction form
    138.88/208.07 = 87.40/x
  3. Step 3: Cross multiply
    138.88x = 208.07 × 87.40
  4. Step 4: Simplify right side
    138.88x = 18,185.32
  5. Step 5: Solve for x
    x = 18,185.32/138.88
  6. Step 6: Final answer
    x = 130.94

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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.