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Finding the Fourth Proportional to 391.34, 539.80 and 280.78

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Solution

The fourth proportional to 391.34, 539.80 and 280.78 is: 387.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    391.34 : 539.80 = 280.78 : x
  2. Step 2: Convert to fraction form
    391.34/539.80 = 280.78/x
  3. Step 3: Cross multiply
    391.34x = 539.80 × 280.78
  4. Step 4: Simplify right side
    391.34x = 151,565.04
  5. Step 5: Solve for x
    x = 151,565.04/391.34
  6. Step 6: Final answer
    x = 387.30

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.