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Finding the Fourth Proportional to 81.16, 112.75 and 80.20

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Solution

The fourth proportional to 81.16, 112.75 and 80.20 is: 111.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.16 : 112.75 = 80.20 : x
  2. Step 2: Convert to fraction form
    81.16/112.75 = 80.20/x
  3. Step 3: Cross multiply
    81.16x = 112.75 × 80.20
  4. Step 4: Simplify right side
    81.16x = 9,042.55
  5. Step 5: Solve for x
    x = 9,042.55/81.16
  6. Step 6: Final answer
    x = 111.42

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.