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Finding the Fourth Proportional to 391.78, 540.66 and 217.13

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Solution

The fourth proportional to 391.78, 540.66 and 217.13 is: 299.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    391.78 : 540.66 = 217.13 : x
  2. Step 2: Convert to fraction form
    391.78/540.66 = 217.13/x
  3. Step 3: Cross multiply
    391.78x = 540.66 × 217.13
  4. Step 4: Simplify right side
    391.78x = 117,391.62
  5. Step 5: Solve for x
    x = 117,391.62/391.78
  6. Step 6: Final answer
    x = 299.64

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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.