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Finding the Fourth Proportional to 81.16, 121.68 and 40.56

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Solution

The fourth proportional to 81.16, 121.68 and 40.56 is: 60.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.16 : 121.68 = 40.56 : x
  2. Step 2: Convert to fraction form
    81.16/121.68 = 40.56/x
  3. Step 3: Cross multiply
    81.16x = 121.68 × 40.56
  4. Step 4: Simplify right side
    81.16x = 4,935.34
  5. Step 5: Solve for x
    x = 4,935.34/81.16
  6. Step 6: Final answer
    x = 60.81

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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.