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Finding the Fourth Proportional to 311.20, 425.72 and 309.76

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Solution

The fourth proportional to 311.20, 425.72 and 309.76 is: 423.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    311.20 : 425.72 = 309.76 : x
  2. Step 2: Convert to fraction form
    311.20/425.72 = 309.76/x
  3. Step 3: Cross multiply
    311.20x = 425.72 × 309.76
  4. Step 4: Simplify right side
    311.20x = 131,871.03
  5. Step 5: Solve for x
    x = 131,871.03/311.20
  6. Step 6: Final answer
    x = 423.75

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.