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Finding the Fourth Proportional to 81.20, 121.62 and 71.12

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Solution

The fourth proportional to 81.20, 121.62 and 71.12 is: 106.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.20 : 121.62 = 71.12 : x
  2. Step 2: Convert to fraction form
    81.20/121.62 = 71.12/x
  3. Step 3: Cross multiply
    81.20x = 121.62 × 71.12
  4. Step 4: Simplify right side
    81.20x = 8,649.61
  5. Step 5: Solve for x
    x = 8,649.61/81.20
  6. Step 6: Final answer
    x = 106.52

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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.