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Finding the Third Proportional to 138.75 and 208.31

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Solution

The third proportional to 138.75 and 208.31 is: 312.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.75 : 208.31 = 208.31 : x
  2. Step 2: Convert to fraction form
    138.75/208.31 = 208.31/x
  3. Step 3: Cross multiply
    138.75x = 208.31 × 208.31
  4. Step 4: Simplify right side
    138.75x = 43,394.10
  5. Step 5: Solve for x
    x = 43,394.10/138.75
  6. Step 6: Final answer
    x = 312.75

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.