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Finding the Fourth Proportional to 391.40, 539.39 and 280.68

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Solution

The fourth proportional to 391.40, 539.39 and 280.68 is: 386.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    391.40 : 539.39 = 280.68 : x
  2. Step 2: Convert to fraction form
    391.40/539.39 = 280.68/x
  3. Step 3: Cross multiply
    391.40x = 539.39 × 280.68
  4. Step 4: Simplify right side
    391.40x = 151,396.12
  5. Step 5: Solve for x
    x = 151,396.12/391.40
  6. Step 6: Final answer
    x = 386.81

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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.