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Finding the Fourth Proportional to 81.68, 121.82 and 70.94

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Solution

The fourth proportional to 81.68, 121.82 and 70.94 is: 105.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.68 : 121.82 = 70.94 : x
  2. Step 2: Convert to fraction form
    81.68/121.82 = 70.94/x
  3. Step 3: Cross multiply
    81.68x = 121.82 × 70.94
  4. Step 4: Simplify right side
    81.68x = 8,641.86
  5. Step 5: Solve for x
    x = 8,641.86/81.68
  6. Step 6: Final answer
    x = 105.81

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.