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Finding the Fourth Proportional to 391.11, 539.70 and 308.40

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Solution

The fourth proportional to 391.11, 539.70 and 308.40 is: 425.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    391.11 : 539.70 = 308.40 : x
  2. Step 2: Convert to fraction form
    391.11/539.70 = 308.40/x
  3. Step 3: Cross multiply
    391.11x = 539.70 × 308.40
  4. Step 4: Simplify right side
    391.11x = 166,443.48
  5. Step 5: Solve for x
    x = 166,443.48/391.11
  6. Step 6: Final answer
    x = 425.57

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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.