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Finding the Fourth Proportional to 81.96, 123.05 and 51.43

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Solution

The fourth proportional to 81.96, 123.05 and 51.43 is: 77.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.96 : 123.05 = 51.43 : x
  2. Step 2: Convert to fraction form
    81.96/123.05 = 51.43/x
  3. Step 3: Cross multiply
    81.96x = 123.05 × 51.43
  4. Step 4: Simplify right side
    81.96x = 6,328.46
  5. Step 5: Solve for x
    x = 6,328.46/81.96
  6. Step 6: Final answer
    x = 77.21

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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.