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Finding the Fourth Proportional to 129.12, 177.12 and 121.56

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Solution

The fourth proportional to 129.12, 177.12 and 121.56 is: 166.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.12 : 177.12 = 121.56 : x
  2. Step 2: Convert to fraction form
    129.12/177.12 = 121.56/x
  3. Step 3: Cross multiply
    129.12x = 177.12 × 121.56
  4. Step 4: Simplify right side
    129.12x = 21,530.71
  5. Step 5: Solve for x
    x = 21,530.71/129.12
  6. Step 6: Final answer
    x = 166.75

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.