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Finding the Fourth Proportional to 121.85, 168.09 and 72.70

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Solution

The fourth proportional to 121.85, 168.09 and 72.70 is: 100.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.85 : 168.09 = 72.70 : x
  2. Step 2: Convert to fraction form
    121.85/168.09 = 72.70/x
  3. Step 3: Cross multiply
    121.85x = 168.09 × 72.70
  4. Step 4: Simplify right side
    121.85x = 12,218.94
  5. Step 5: Solve for x
    x = 12,218.94/121.85
  6. Step 6: Final answer
    x = 100.28

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.