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Finding the Fourth Proportional to 84.20, 125.96 and 72.80

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Solution

The fourth proportional to 84.20, 125.96 and 72.80 is: 108.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    84.20 : 125.96 = 72.80 : x
  2. Step 2: Convert to fraction form
    84.20/125.96 = 72.80/x
  3. Step 3: Cross multiply
    84.20x = 125.96 × 72.80
  4. Step 4: Simplify right side
    84.20x = 9,169.89
  5. Step 5: Solve for x
    x = 9,169.89/84.20
  6. Step 6: Final answer
    x = 108.91

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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.