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Finding the Third Proportional to 387.50 and 639.25

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Solution

The third proportional to 387.50 and 639.25 is: 1,054.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    387.50 : 639.25 = 639.25 : x
  2. Step 2: Convert to fraction form
    387.50/639.25 = 639.25/x
  3. Step 3: Cross multiply
    387.50x = 639.25 × 639.25
  4. Step 4: Simplify right side
    387.50x = 408,640.56
  5. Step 5: Solve for x
    x = 408,640.56/387.50
  6. Step 6: Final answer
    x = 1,054.56

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Why These Related Problems?

These problems maintain the same ratio (1.65) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.