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Finding the Fourth Proportional to 81.66, 112.58 and 80.78

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Solution

The fourth proportional to 81.66, 112.58 and 80.78 is: 111.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.66 : 112.58 = 80.78 : x
  2. Step 2: Convert to fraction form
    81.66/112.58 = 80.78/x
  3. Step 3: Cross multiply
    81.66x = 112.58 × 80.78
  4. Step 4: Simplify right side
    81.66x = 9,094.21
  5. Step 5: Solve for x
    x = 9,094.21/81.66
  6. Step 6: Final answer
    x = 111.37

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.