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Finding the Fourth Proportional to 87.35, 121.39 and 86.43

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Solution

The fourth proportional to 87.35, 121.39 and 86.43 is: 120.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.35 : 121.39 = 86.43 : x
  2. Step 2: Convert to fraction form
    87.35/121.39 = 86.43/x
  3. Step 3: Cross multiply
    87.35x = 121.39 × 86.43
  4. Step 4: Simplify right side
    87.35x = 10,491.98
  5. Step 5: Solve for x
    x = 10,491.98/87.35
  6. Step 6: Final answer
    x = 120.12

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.