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Finding the Fourth Proportional to 87.15, 129.87 and 84.80

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Solution

The fourth proportional to 87.15, 129.87 and 84.80 is: 126.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.15 : 129.87 = 84.80 : x
  2. Step 2: Convert to fraction form
    87.15/129.87 = 84.80/x
  3. Step 3: Cross multiply
    87.15x = 129.87 × 84.80
  4. Step 4: Simplify right side
    87.15x = 11,012.33
  5. Step 5: Solve for x
    x = 11,012.33/87.15
  6. Step 6: Final answer
    x = 126.36

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.