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Finding the Fourth Proportional to 391.28, 587.12 and 198.80

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Solution

The fourth proportional to 391.28, 587.12 and 198.80 is: 298.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    391.28 : 587.12 = 198.80 : x
  2. Step 2: Convert to fraction form
    391.28/587.12 = 198.80/x
  3. Step 3: Cross multiply
    391.28x = 587.12 × 198.80
  4. Step 4: Simplify right side
    391.28x = 116,719.46
  5. Step 5: Solve for x
    x = 116,719.46/391.28
  6. Step 6: Final answer
    x = 298.30

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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.