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Finding the Fourth Proportional to 81.28, 111.90 and 68.98

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Solution

The fourth proportional to 81.28, 111.90 and 68.98 is: 94.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.28 : 111.90 = 68.98 : x
  2. Step 2: Convert to fraction form
    81.28/111.90 = 68.98/x
  3. Step 3: Cross multiply
    81.28x = 111.90 × 68.98
  4. Step 4: Simplify right side
    81.28x = 7,718.86
  5. Step 5: Solve for x
    x = 7,718.86/81.28
  6. Step 6: Final answer
    x = 94.97

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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.