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Finding the Third Proportional to 121 and 128

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Solution

The third proportional to 121 and 128 is: 135.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    121 : 128 = 128 : x
  2. Step 2: Convert to fraction form
    121/128 = 128/x
  3. Step 3: Cross multiply
    121x = 128 × 128
  4. Step 4: Simplify right side
    121x = 16,384
  5. Step 5: Solve for x
    x = 16,384/121
  6. Step 6: Final answer
    x = 135.40

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Why These Related Problems?

These problems maintain the same ratio (1.06) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.