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Finding the Fourth Proportional to 105.72, 158.30 and 81.56

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Solution

The fourth proportional to 105.72, 158.30 and 81.56 is: 122.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    105.72 : 158.30 = 81.56 : x
  2. Step 2: Convert to fraction form
    105.72/158.30 = 81.56/x
  3. Step 3: Cross multiply
    105.72x = 158.30 × 81.56
  4. Step 4: Simplify right side
    105.72x = 12,910.95
  5. Step 5: Solve for x
    x = 12,910.95/105.72
  6. Step 6: Final answer
    x = 122.12

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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.