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Finding the Fourth Proportional to 138.95, 207.99 and 87.42

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Solution

The fourth proportional to 138.95, 207.99 and 87.42 is: 130.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.95 : 207.99 = 87.42 : x
  2. Step 2: Convert to fraction form
    138.95/207.99 = 87.42/x
  3. Step 3: Cross multiply
    138.95x = 207.99 × 87.42
  4. Step 4: Simplify right side
    138.95x = 18,181.71
  5. Step 5: Solve for x
    x = 18,181.71/138.95
  6. Step 6: Final answer
    x = 130.85

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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.