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Finding the Fourth Proportional to 142.30, 213.19 and 81.34

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Solution

The fourth proportional to 142.30, 213.19 and 81.34 is: 121.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    142.30 : 213.19 = 81.34 : x
  2. Step 2: Convert to fraction form
    142.30/213.19 = 81.34/x
  3. Step 3: Cross multiply
    142.30x = 213.19 × 81.34
  4. Step 4: Simplify right side
    142.30x = 17,340.87
  5. Step 5: Solve for x
    x = 17,340.87/142.30
  6. Step 6: Final answer
    x = 121.86

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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.