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Finding the Fourth Proportional to 309.20, 463.78 and 81.20

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Solution

The fourth proportional to 309.20, 463.78 and 81.20 is: 121.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    309.20 : 463.78 = 81.20 : x
  2. Step 2: Convert to fraction form
    309.20/463.78 = 81.20/x
  3. Step 3: Cross multiply
    309.20x = 463.78 × 81.20
  4. Step 4: Simplify right side
    309.20x = 37,658.94
  5. Step 5: Solve for x
    x = 37,658.94/309.20
  6. Step 6: Final answer
    x = 121.79

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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.