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Finding the Fourth Proportional to 129.84, 178.74 and 121.92

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Solution

The fourth proportional to 129.84, 178.74 and 121.92 is: 167.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.84 : 178.74 = 121.92 : x
  2. Step 2: Convert to fraction form
    129.84/178.74 = 121.92/x
  3. Step 3: Cross multiply
    129.84x = 178.74 × 121.92
  4. Step 4: Simplify right side
    129.84x = 21,791.98
  5. Step 5: Solve for x
    x = 21,791.98/129.84
  6. Step 6: Final answer
    x = 167.84

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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.