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Finding the Fourth Proportional to 90.18, 135.09 and 86.31

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Solution

The fourth proportional to 90.18, 135.09 and 86.31 is: 129.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.18 : 135.09 = 86.31 : x
  2. Step 2: Convert to fraction form
    90.18/135.09 = 86.31/x
  3. Step 3: Cross multiply
    90.18x = 135.09 × 86.31
  4. Step 4: Simplify right side
    90.18x = 11,659.62
  5. Step 5: Solve for x
    x = 11,659.62/90.18
  6. Step 6: Final answer
    x = 129.29

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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.