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Finding the Fourth Proportional to 90.87, 125.42 and 81.64

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Solution

The fourth proportional to 90.87, 125.42 and 81.64 is: 112.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.87 : 125.42 = 81.64 : x
  2. Step 2: Convert to fraction form
    90.87/125.42 = 81.64/x
  3. Step 3: Cross multiply
    90.87x = 125.42 × 81.64
  4. Step 4: Simplify right side
    90.87x = 10,238.88
  5. Step 5: Solve for x
    x = 10,238.88/90.87
  6. Step 6: Final answer
    x = 112.68

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.