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Finding the Fourth Proportional to 87.72, 130.86 and 86.28

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Solution

The fourth proportional to 87.72, 130.86 and 86.28 is: 128.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.72 : 130.86 = 86.28 : x
  2. Step 2: Convert to fraction form
    87.72/130.86 = 86.28/x
  3. Step 3: Cross multiply
    87.72x = 130.86 × 86.28
  4. Step 4: Simplify right side
    87.72x = 11,290.60
  5. Step 5: Solve for x
    x = 11,290.60/87.72
  6. Step 6: Final answer
    x = 128.71

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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.