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Finding the Fourth Proportional to 391.80, 540.68 and 217.15

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Solution

The fourth proportional to 391.80, 540.68 and 217.15 is: 299.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    391.80 : 540.68 = 217.15 : x
  2. Step 2: Convert to fraction form
    391.80/540.68 = 217.15/x
  3. Step 3: Cross multiply
    391.80x = 540.68 × 217.15
  4. Step 4: Simplify right side
    391.80x = 117,408.66
  5. Step 5: Solve for x
    x = 117,408.66/391.80
  6. Step 6: Final answer
    x = 299.66

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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.