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Finding the Fourth Proportional to 81.63, 111.78 and 80.28

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Solution

The fourth proportional to 81.63, 111.78 and 80.28 is: 109.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.63 : 111.78 = 80.28 : x
  2. Step 2: Convert to fraction form
    81.63/111.78 = 80.28/x
  3. Step 3: Cross multiply
    81.63x = 111.78 × 80.28
  4. Step 4: Simplify right side
    81.63x = 8,973.70
  5. Step 5: Solve for x
    x = 8,973.70/81.63
  6. Step 6: Final answer
    x = 109.93

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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.