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Finding the Fourth Proportional to 86.14, 128.66 and 71.61

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Solution

The fourth proportional to 86.14, 128.66 and 71.61 is: 106.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.14 : 128.66 = 71.61 : x
  2. Step 2: Convert to fraction form
    86.14/128.66 = 71.61/x
  3. Step 3: Cross multiply
    86.14x = 128.66 × 71.61
  4. Step 4: Simplify right side
    86.14x = 9,213.34
  5. Step 5: Solve for x
    x = 9,213.34/86.14
  6. Step 6: Final answer
    x = 106.96

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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.