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Finding the Fourth Proportional to 81.60, 109.20 and 81.60

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Solution

The fourth proportional to 81.60, 109.20 and 81.60 is: 109.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.60 : 109.20 = 81.60 : x
  2. Step 2: Convert to fraction form
    81.60/109.20 = 81.60/x
  3. Step 3: Cross multiply
    81.60x = 109.20 × 81.60
  4. Step 4: Simplify right side
    81.60x = 8,910.72
  5. Step 5: Solve for x
    x = 8,910.72/81.60
  6. Step 6: Final answer
    x = 109.20

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Why These Related Problems?

These problems maintain the same ratio (1.34) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.