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Finding the Fourth Proportional to 87.38, 131.16 and 85.42

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Solution

The fourth proportional to 87.38, 131.16 and 85.42 is: 128.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.38 : 131.16 = 85.42 : x
  2. Step 2: Convert to fraction form
    87.38/131.16 = 85.42/x
  3. Step 3: Cross multiply
    87.38x = 131.16 × 85.42
  4. Step 4: Simplify right side
    87.38x = 11,203.50
  5. Step 5: Solve for x
    x = 11,203.50/87.38
  6. Step 6: Final answer
    x = 128.22

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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.