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Finding the Fourth Proportional to 521.20, 781.80 and 278.20

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Solution

The fourth proportional to 521.20, 781.80 and 278.20 is: 417.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    521.20 : 781.80 = 278.20 : x
  2. Step 2: Convert to fraction form
    521.20/781.80 = 278.20/x
  3. Step 3: Cross multiply
    521.20x = 781.80 × 278.20
  4. Step 4: Simplify right side
    521.20x = 217,496.76
  5. Step 5: Solve for x
    x = 217,496.76/521.20
  6. Step 6: Final answer
    x = 417.30

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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.