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Finding the Fourth Proportional to 81.21, 121.84 and 40.64

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Solution

The fourth proportional to 81.21, 121.84 and 40.64 is: 60.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.21 : 121.84 = 40.64 : x
  2. Step 2: Convert to fraction form
    81.21/121.84 = 40.64/x
  3. Step 3: Cross multiply
    81.21x = 121.84 × 40.64
  4. Step 4: Simplify right side
    81.21x = 4,950.87
  5. Step 5: Solve for x
    x = 4,950.87/81.21
  6. Step 6: Final answer
    x = 60.96

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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.