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Finding the Third Proportional to 128.81 and 198.84

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Solution

The third proportional to 128.81 and 198.84 is: 306.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.81 : 198.84 = 198.84 : x
  2. Step 2: Convert to fraction form
    128.81/198.84 = 198.84/x
  3. Step 3: Cross multiply
    128.81x = 198.84 × 198.84
  4. Step 4: Simplify right side
    128.81x = 39,538.84
  5. Step 5: Solve for x
    x = 39,538.84/128.81
  6. Step 6: Final answer
    x = 306.95

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Why These Related Problems?

These problems maintain the same ratio (1.54) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.