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Finding the Fourth Proportional to 391.78, 587.61 and 135.28

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Solution

The fourth proportional to 391.78, 587.61 and 135.28 is: 202.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    391.78 : 587.61 = 135.28 : x
  2. Step 2: Convert to fraction form
    391.78/587.61 = 135.28/x
  3. Step 3: Cross multiply
    391.78x = 587.61 × 135.28
  4. Step 4: Simplify right side
    391.78x = 79,491.88
  5. Step 5: Solve for x
    x = 79,491.88/391.78
  6. Step 6: Final answer
    x = 202.90

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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.