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Finding the Fourth Proportional to 129.26, 178.40 and 121.45

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Solution

The fourth proportional to 129.26, 178.40 and 121.45 is: 167.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.26 : 178.40 = 121.45 : x
  2. Step 2: Convert to fraction form
    129.26/178.40 = 121.45/x
  3. Step 3: Cross multiply
    129.26x = 178.40 × 121.45
  4. Step 4: Simplify right side
    129.26x = 21,666.68
  5. Step 5: Solve for x
    x = 21,666.68/129.26
  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.