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Finding the Fourth Proportional to 128.27, 177.83 and 121.68

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Solution

The fourth proportional to 128.27, 177.83 and 121.68 is: 168.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.27 : 177.83 = 121.68 : x
  2. Step 2: Convert to fraction form
    128.27/177.83 = 121.68/x
  3. Step 3: Cross multiply
    128.27x = 177.83 × 121.68
  4. Step 4: Simplify right side
    128.27x = 21,638.35
  5. Step 5: Solve for x
    x = 21,638.35/128.27
  6. Step 6: Final answer
    x = 168.69

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.