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Finding the Fourth Proportional to 103.20, 142.54 and 85.78

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Solution

The fourth proportional to 103.20, 142.54 and 85.78 is: 118.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    103.20 : 142.54 = 85.78 : x
  2. Step 2: Convert to fraction form
    103.20/142.54 = 85.78/x
  3. Step 3: Cross multiply
    103.20x = 142.54 × 85.78
  4. Step 4: Simplify right side
    103.20x = 12,227.30
  5. Step 5: Solve for x
    x = 12,227.30/103.20
  6. Step 6: Final answer
    x = 118.49

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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.