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Finding the Fourth Proportional to 121.99, 168.31 and 72.85

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Solution

The fourth proportional to 121.99, 168.31 and 72.85 is: 100.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.99 : 168.31 = 72.85 : x
  2. Step 2: Convert to fraction form
    121.99/168.31 = 72.85/x
  3. Step 3: Cross multiply
    121.99x = 168.31 × 72.85
  4. Step 4: Simplify right side
    121.99x = 12,261.38
  5. Step 5: Solve for x
    x = 12,261.38/121.99
  6. Step 6: Final answer
    x = 100.51

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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.