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Finding the Fourth Proportional to 81.76, 123.08 and 71.82

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Solution

The fourth proportional to 81.76, 123.08 and 71.82 is: 108.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.76 : 123.08 = 71.82 : x
  2. Step 2: Convert to fraction form
    81.76/123.08 = 71.82/x
  3. Step 3: Cross multiply
    81.76x = 123.08 × 71.82
  4. Step 4: Simplify right side
    81.76x = 8,839.61
  5. Step 5: Solve for x
    x = 8,839.61/81.76
  6. Step 6: Final answer
    x = 108.12

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.