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Finding the Fourth Proportional to 521.28, 781.24 and 212.78

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Solution

The fourth proportional to 521.28, 781.24 and 212.78 is: 318.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    521.28 : 781.24 = 212.78 : x
  2. Step 2: Convert to fraction form
    521.28/781.24 = 212.78/x
  3. Step 3: Cross multiply
    521.28x = 781.24 × 212.78
  4. Step 4: Simplify right side
    521.28x = 166,228.34
  5. Step 5: Solve for x
    x = 166,228.34/521.28
  6. Step 6: Final answer
    x = 318.88

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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.