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Finding the Fourth Proportional to 81.32, 121.55 and 70.61

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Solution

The fourth proportional to 81.32, 121.55 and 70.61 is: 105.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.32 : 121.55 = 70.61 : x
  2. Step 2: Convert to fraction form
    81.32/121.55 = 70.61/x
  3. Step 3: Cross multiply
    81.32x = 121.55 × 70.61
  4. Step 4: Simplify right side
    81.32x = 8,582.65
  5. Step 5: Solve for x
    x = 8,582.65/81.32
  6. Step 6: Final answer
    x = 105.54

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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.