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Finding the Fourth Proportional to 138.15, 207.42 and 86.64

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Solution

The fourth proportional to 138.15, 207.42 and 86.64 is: 130.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.15 : 207.42 = 86.64 : x
  2. Step 2: Convert to fraction form
    138.15/207.42 = 86.64/x
  3. Step 3: Cross multiply
    138.15x = 207.42 × 86.64
  4. Step 4: Simplify right side
    138.15x = 17,970.87
  5. Step 5: Solve for x
    x = 17,970.87/138.15
  6. Step 6: Final answer
    x = 130.08

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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.