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Finding the Fourth Proportional to 81.21, 111.98 and 68.74

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Solution

The fourth proportional to 81.21, 111.98 and 68.74 is: 94.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.21 : 111.98 = 68.74 : x
  2. Step 2: Convert to fraction form
    81.21/111.98 = 68.74/x
  3. Step 3: Cross multiply
    81.21x = 111.98 × 68.74
  4. Step 4: Simplify right side
    81.21x = 7,697.51
  5. Step 5: Solve for x
    x = 7,697.51/81.21
  6. Step 6: Final answer
    x = 94.79

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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.