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Finding the Fourth Proportional to 81.40, 122.56 and 71.83

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Solution

The fourth proportional to 81.40, 122.56 and 71.83 is: 108.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.40 : 122.56 = 71.83 : x
  2. Step 2: Convert to fraction form
    81.40/122.56 = 71.83/x
  3. Step 3: Cross multiply
    81.40x = 122.56 × 71.83
  4. Step 4: Simplify right side
    81.40x = 8,803.13
  5. Step 5: Solve for x
    x = 8,803.13/81.40
  6. Step 6: Final answer
    x = 108.15

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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.