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Finding the Fourth Proportional to 81.24, 121.68 and 61.12

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Solution

The fourth proportional to 81.24, 121.68 and 61.12 is: 91.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.24 : 121.68 = 61.12 : x
  2. Step 2: Convert to fraction form
    81.24/121.68 = 61.12/x
  3. Step 3: Cross multiply
    81.24x = 121.68 × 61.12
  4. Step 4: Simplify right side
    81.24x = 7,437.08
  5. Step 5: Solve for x
    x = 7,437.08/81.24
  6. Step 6: Final answer
    x = 91.54

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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.