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Finding the Fourth Proportional to 86.32, 128.85 and 71.74

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Solution

The fourth proportional to 86.32, 128.85 and 71.74 is: 107.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.32 : 128.85 = 71.74 : x
  2. Step 2: Convert to fraction form
    86.32/128.85 = 71.74/x
  3. Step 3: Cross multiply
    86.32x = 128.85 × 71.74
  4. Step 4: Simplify right side
    86.32x = 9,243.38
  5. Step 5: Solve for x
    x = 9,243.38/86.32
  6. Step 6: Final answer
    x = 107.09

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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.