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Finding the Third Proportional to 421.75 and 639.25

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Solution

The third proportional to 421.75 and 639.25 is: 968.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.75 : 639.25 = 639.25 : x
  2. Step 2: Convert to fraction form
    421.75/639.25 = 639.25/x
  3. Step 3: Cross multiply
    421.75x = 639.25 × 639.25
  4. Step 4: Simplify right side
    421.75x = 408,640.56
  5. Step 5: Solve for x
    x = 408,640.56/421.75
  6. Step 6: Final answer
    x = 968.92

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These problems maintain the same ratio (1.52) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.