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Finding the Fourth Proportional to 81.99, 122.31 and 69.21

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Solution

The fourth proportional to 81.99, 122.31 and 69.21 is: 103.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.99 : 122.31 = 69.21 : x
  2. Step 2: Convert to fraction form
    81.99/122.31 = 69.21/x
  3. Step 3: Cross multiply
    81.99x = 122.31 × 69.21
  4. Step 4: Simplify right side
    81.99x = 8,465.08
  5. Step 5: Solve for x
    x = 8,465.08/81.99
  6. Step 6: Final answer
    x = 103.25

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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.