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Finding the Third Proportional to 128.67 and 199.76

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Solution

The third proportional to 128.67 and 199.76 is: 310.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.67 : 199.76 = 199.76 : x
  2. Step 2: Convert to fraction form
    128.67/199.76 = 199.76/x
  3. Step 3: Cross multiply
    128.67x = 199.76 × 199.76
  4. Step 4: Simplify right side
    128.67x = 39,903.18
  5. Step 5: Solve for x
    x = 39,903.18/128.67
  6. Step 6: Final answer
    x = 310.12

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Why These Related Problems?

These problems maintain the same ratio (1.55) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.