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Finding the Fourth Proportional to 391.87, 540.78 and 217.22

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Solution

The fourth proportional to 391.87, 540.78 and 217.22 is: 299.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    391.87 : 540.78 = 217.22 : x
  2. Step 2: Convert to fraction form
    391.87/540.78 = 217.22/x
  3. Step 3: Cross multiply
    391.87x = 540.78 × 217.22
  4. Step 4: Simplify right side
    391.87x = 117,468.23
  5. Step 5: Solve for x
    x = 117,468.23/391.87
  6. Step 6: Final answer
    x = 299.76

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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.