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Finding the Fourth Proportional to 139.12, 191.82 and 121.57

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Solution

The fourth proportional to 139.12, 191.82 and 121.57 is: 167.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.12 : 191.82 = 121.57 : x
  2. Step 2: Convert to fraction form
    139.12/191.82 = 121.57/x
  3. Step 3: Cross multiply
    139.12x = 191.82 × 121.57
  4. Step 4: Simplify right side
    139.12x = 23,319.56
  5. Step 5: Solve for x
    x = 23,319.56/139.12
  6. Step 6: Final answer
    x = 167.62

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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.