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Finding the Third Proportional to 87.61 and 128.39

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Solution

The third proportional to 87.61 and 128.39 is: 188.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.61 : 128.39 = 128.39 : x
  2. Step 2: Convert to fraction form
    87.61/128.39 = 128.39/x
  3. Step 3: Cross multiply
    87.61x = 128.39 × 128.39
  4. Step 4: Simplify right side
    87.61x = 16,484.15
  5. Step 5: Solve for x
    x = 16,484.15/87.61
  6. Step 6: Final answer
    x = 188.16

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Why These Related Problems?

These problems maintain the same ratio (1.47) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.