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Finding the Fourth Proportional to 129.72, 178.74 and 121.08

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Solution

The fourth proportional to 129.72, 178.74 and 121.08 is: 166.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.72 : 178.74 = 121.08 : x
  2. Step 2: Convert to fraction form
    129.72/178.74 = 121.08/x
  3. Step 3: Cross multiply
    129.72x = 178.74 × 121.08
  4. Step 4: Simplify right side
    129.72x = 21,641.84
  5. Step 5: Solve for x
    x = 21,641.84/129.72
  6. Step 6: Final answer
    x = 166.84

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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.