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Finding the Fourth Proportional to 81.12, 120.96 and 71.88

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Solution

The fourth proportional to 81.12, 120.96 and 71.88 is: 107.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.12 : 120.96 = 71.88 : x
  2. Step 2: Convert to fraction form
    81.12/120.96 = 71.88/x
  3. Step 3: Cross multiply
    81.12x = 120.96 × 71.88
  4. Step 4: Simplify right side
    81.12x = 8,694.60
  5. Step 5: Solve for x
    x = 8,694.60/81.12
  6. Step 6: Final answer
    x = 107.18

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.