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Finding the Fourth Proportional to 81.15, 121.74 and 45.09

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Solution

The fourth proportional to 81.15, 121.74 and 45.09 is: 67.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.15 : 121.74 = 45.09 : x
  2. Step 2: Convert to fraction form
    81.15/121.74 = 45.09/x
  3. Step 3: Cross multiply
    81.15x = 121.74 × 45.09
  4. Step 4: Simplify right side
    81.15x = 5,489.26
  5. Step 5: Solve for x
    x = 5,489.26/81.15
  6. Step 6: Final answer
    x = 67.64

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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.