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Finding the Fourth Proportional to 121.98, 168.36 and 72.90

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Solution

The fourth proportional to 121.98, 168.36 and 72.90 is: 100.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.98 : 168.36 = 72.90 : x
  2. Step 2: Convert to fraction form
    121.98/168.36 = 72.90/x
  3. Step 3: Cross multiply
    121.98x = 168.36 × 72.90
  4. Step 4: Simplify right side
    121.98x = 12,273.44
  5. Step 5: Solve for x
    x = 12,273.44/121.98
  6. Step 6: Final answer
    x = 100.62

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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.