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Finding the Third Proportional to 128.75 and 211.50

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Solution

The third proportional to 128.75 and 211.50 is: 347.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.75 : 211.50 = 211.50 : x
  2. Step 2: Convert to fraction form
    128.75/211.50 = 211.50/x
  3. Step 3: Cross multiply
    128.75x = 211.50 × 211.50
  4. Step 4: Simplify right side
    128.75x = 44,732.25
  5. Step 5: Solve for x
    x = 44,732.25/128.75
  6. Step 6: Final answer
    x = 347.43

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Why These Related Problems?

These problems maintain the same ratio (1.64) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.