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Finding the Fourth Proportional to 81.28, 121.80 and 45.22

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Solution

The fourth proportional to 81.28, 121.80 and 45.22 is: 67.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.28 : 121.80 = 45.22 : x
  2. Step 2: Convert to fraction form
    81.28/121.80 = 45.22/x
  3. Step 3: Cross multiply
    81.28x = 121.80 × 45.22
  4. Step 4: Simplify right side
    81.28x = 5,507.80
  5. Step 5: Solve for x
    x = 5,507.80/81.28
  6. Step 6: Final answer
    x = 67.76

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.