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Finding the Fourth Proportional to 521.67, 781.47 and 391.81

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Solution

The fourth proportional to 521.67, 781.47 and 391.81 is: 586.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    521.67 : 781.47 = 391.81 : x
  2. Step 2: Convert to fraction form
    521.67/781.47 = 391.81/x
  3. Step 3: Cross multiply
    521.67x = 781.47 × 391.81
  4. Step 4: Simplify right side
    521.67x = 306,187.76
  5. Step 5: Solve for x
    x = 306,187.76/521.67
  6. Step 6: Final answer
    x = 586.94

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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.