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Finding the Fourth Proportional to 81.75, 122.58 and 72.75

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Solution

The fourth proportional to 81.75, 122.58 and 72.75 is: 109.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.75 : 122.58 = 72.75 : x
  2. Step 2: Convert to fraction form
    81.75/122.58 = 72.75/x
  3. Step 3: Cross multiply
    81.75x = 122.58 × 72.75
  4. Step 4: Simplify right side
    81.75x = 8,917.70
  5. Step 5: Solve for x
    x = 8,917.70/81.75
  6. Step 6: Final answer
    x = 109.08

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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.