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Finding the Fourth Proportional to 102.78, 154.08 and 86.58

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Solution

The fourth proportional to 102.78, 154.08 and 86.58 is: 129.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    102.78 : 154.08 = 86.58 : x
  2. Step 2: Convert to fraction form
    102.78/154.08 = 86.58/x
  3. Step 3: Cross multiply
    102.78x = 154.08 × 86.58
  4. Step 4: Simplify right side
    102.78x = 13,340.25
  5. Step 5: Solve for x
    x = 13,340.25/102.78
  6. Step 6: Final answer
    x = 129.79

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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.