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Finding the Third Proportional to 128 and 155

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Solution

The third proportional to 128 and 155 is: 187.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    128 : 155 = 155 : x
  2. Step 2: Convert to fraction form
    128/155 = 155/x
  3. Step 3: Cross multiply
    128x = 155 × 155
  4. Step 4: Simplify right side
    128x = 24,025
  5. Step 5: Solve for x
    x = 24,025/128
  6. Step 6: Final answer
    x = 187.70

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Why These Related Problems?

These problems maintain the same ratio (1.21) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.