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Finding the Fourth Proportional to 521.38, 781.35 and 399.58

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Solution

The fourth proportional to 521.38, 781.35 and 399.58 is: 598.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    521.38 : 781.35 = 399.58 : x
  2. Step 2: Convert to fraction form
    521.38/781.35 = 399.58/x
  3. Step 3: Cross multiply
    521.38x = 781.35 × 399.58
  4. Step 4: Simplify right side
    521.38x = 312,211.83
  5. Step 5: Solve for x
    x = 312,211.83/521.38
  6. Step 6: Final answer
    x = 598.82

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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.