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Finding the Fourth Proportional to 81.42, 111.59 and 80.79

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Solution

The fourth proportional to 81.42, 111.59 and 80.79 is: 110.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.42 : 111.59 = 80.79 : x
  2. Step 2: Convert to fraction form
    81.42/111.59 = 80.79/x
  3. Step 3: Cross multiply
    81.42x = 111.59 × 80.79
  4. Step 4: Simplify right side
    81.42x = 9,014.95
  5. Step 5: Solve for x
    x = 9,014.95/81.42
  6. Step 6: Final answer
    x = 110.72

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.