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Finding the Fourth Proportional to 521.13, 781.19 and 399.90

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Solution

The fourth proportional to 521.13, 781.19 and 399.90 is: 599.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    521.13 : 781.19 = 399.90 : x
  2. Step 2: Convert to fraction form
    521.13/781.19 = 399.90/x
  3. Step 3: Cross multiply
    521.13x = 781.19 × 399.90
  4. Step 4: Simplify right side
    521.13x = 312,397.88
  5. Step 5: Solve for x
    x = 312,397.88/521.13
  6. Step 6: Final answer
    x = 599.46

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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.