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Finding the Fourth Proportional to 138.42, 207.38 and 86.99

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Solution

The fourth proportional to 138.42, 207.38 and 86.99 is: 130.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.42 : 207.38 = 86.99 : x
  2. Step 2: Convert to fraction form
    138.42/207.38 = 86.99/x
  3. Step 3: Cross multiply
    138.42x = 207.38 × 86.99
  4. Step 4: Simplify right side
    138.42x = 18,039.17
  5. Step 5: Solve for x
    x = 18,039.17/138.42
  6. Step 6: Final answer
    x = 130.32

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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.