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Finding the Fourth Proportional to 81.65, 122.90 and 70.47

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Solution

The fourth proportional to 81.65, 122.90 and 70.47 is: 106.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.65 : 122.90 = 70.47 : x
  2. Step 2: Convert to fraction form
    81.65/122.90 = 70.47/x
  3. Step 3: Cross multiply
    81.65x = 122.90 × 70.47
  4. Step 4: Simplify right side
    81.65x = 8,660.41
  5. Step 5: Solve for x
    x = 8,660.41/81.65
  6. Step 6: Final answer
    x = 106.07

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.