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Finding the Third Proportional to 378.75 and 640.31

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Solution

The third proportional to 378.75 and 640.31 is: 1,082.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    378.75 : 640.31 = 640.31 : x
  2. Step 2: Convert to fraction form
    378.75/640.31 = 640.31/x
  3. Step 3: Cross multiply
    378.75x = 640.31 × 640.31
  4. Step 4: Simplify right side
    378.75x = 410,000.10
  5. Step 5: Solve for x
    x = 410,000.10/378.75
  6. Step 6: Final answer
    x = 1,082.51

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Why These Related Problems?

These problems maintain the same ratio (1.69) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.