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Finding the Fourth Proportional to 521.47, 781.99 and 261.40

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Solution

The fourth proportional to 521.47, 781.99 and 261.40 is: 391.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    521.47 : 781.99 = 261.40 : x
  2. Step 2: Convert to fraction form
    521.47/781.99 = 261.40/x
  3. Step 3: Cross multiply
    521.47x = 781.99 × 261.40
  4. Step 4: Simplify right side
    521.47x = 204,412.19
  5. Step 5: Solve for x
    x = 204,412.19/521.47
  6. Step 6: Final answer
    x = 391.99

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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.