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Finding the Fourth Proportional to 521.39, 781.31 and 212.87

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Solution

The fourth proportional to 521.39, 781.31 and 212.87 is: 318.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    521.39 : 781.31 = 212.87 : x
  2. Step 2: Convert to fraction form
    521.39/781.31 = 212.87/x
  3. Step 3: Cross multiply
    521.39x = 781.31 × 212.87
  4. Step 4: Simplify right side
    521.39x = 166,317.46
  5. Step 5: Solve for x
    x = 166,317.46/521.39
  6. Step 6: Final answer
    x = 318.99

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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.