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Finding the Fourth Proportional to 90.87, 136.31 and 86.01

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Solution

The fourth proportional to 90.87, 136.31 and 86.01 is: 129.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.87 : 136.31 = 86.01 : x
  2. Step 2: Convert to fraction form
    90.87/136.31 = 86.01/x
  3. Step 3: Cross multiply
    90.87x = 136.31 × 86.01
  4. Step 4: Simplify right side
    90.87x = 11,723.59
  5. Step 5: Solve for x
    x = 11,723.59/90.87
  6. Step 6: Final answer
    x = 129.02

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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.