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Finding the Fourth Proportional to 391.20, 586.80 and 217.92

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Solution

The fourth proportional to 391.20, 586.80 and 217.92 is: 326.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    391.20 : 586.80 = 217.92 : x
  2. Step 2: Convert to fraction form
    391.20/586.80 = 217.92/x
  3. Step 3: Cross multiply
    391.20x = 586.80 × 217.92
  4. Step 4: Simplify right side
    391.20x = 127,875.46
  5. Step 5: Solve for x
    x = 127,875.46/391.20
  6. Step 6: Final answer
    x = 326.88

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.