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Finding the Fourth Proportional to 86.50, 129.61 and 85.56

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Solution

The fourth proportional to 86.50, 129.61 and 85.56 is: 128.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.50 : 129.61 = 85.56 : x
  2. Step 2: Convert to fraction form
    86.50/129.61 = 85.56/x
  3. Step 3: Cross multiply
    86.50x = 129.61 × 85.56
  4. Step 4: Simplify right side
    86.50x = 11,089.43
  5. Step 5: Solve for x
    x = 11,089.43/86.50
  6. Step 6: Final answer
    x = 128.20

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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.