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Finding the Fourth Proportional to 142.42, 213.88 and 85

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Solution

The fourth proportional to 142.42, 213.88 and 85 is: 127.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    142.42 : 213.88 = 85 : x
  2. Step 2: Convert to fraction form
    142.42/213.88 = 85/x
  3. Step 3: Cross multiply
    142.42x = 213.88 × 85
  4. Step 4: Simplify right side
    142.42x = 18,179.80
  5. Step 5: Solve for x
    x = 18,179.80/142.42
  6. Step 6: Final answer
    x = 127.65

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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.