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Finding the Fourth Proportional to 81.76, 121.92 and 80.48

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Solution

The fourth proportional to 81.76, 121.92 and 80.48 is: 120.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.76 : 121.92 = 80.48 : x
  2. Step 2: Convert to fraction form
    81.76/121.92 = 80.48/x
  3. Step 3: Cross multiply
    81.76x = 121.92 × 80.48
  4. Step 4: Simplify right side
    81.76x = 9,812.12
  5. Step 5: Solve for x
    x = 9,812.12/81.76
  6. Step 6: Final answer
    x = 120.01

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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.