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Finding the Fourth Proportional to 102.90, 154.15 and 86.75

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Solution

The fourth proportional to 102.90, 154.15 and 86.75 is: 129.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    102.90 : 154.15 = 86.75 : x
  2. Step 2: Convert to fraction form
    102.90/154.15 = 86.75/x
  3. Step 3: Cross multiply
    102.90x = 154.15 × 86.75
  4. Step 4: Simplify right side
    102.90x = 13,372.16
  5. Step 5: Solve for x
    x = 13,372.16/102.90
  6. Step 6: Final answer
    x = 129.96

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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.