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Finding the Fourth Proportional to 86.56, 129.75 and 81.76

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Solution

The fourth proportional to 86.56, 129.75 and 81.76 is: 122.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.56 : 129.75 = 81.76 : x
  2. Step 2: Convert to fraction form
    86.56/129.75 = 81.76/x
  3. Step 3: Cross multiply
    86.56x = 129.75 × 81.76
  4. Step 4: Simplify right side
    86.56x = 10,608.36
  5. Step 5: Solve for x
    x = 10,608.36/86.56
  6. Step 6: Final answer
    x = 122.55

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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.