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Finding the Third Proportional to 258 and 639.75

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Solution

The third proportional to 258 and 639.75 is: 1,586.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    258 : 639.75 = 639.75 : x
  2. Step 2: Convert to fraction form
    258/639.75 = 639.75/x
  3. Step 3: Cross multiply
    258x = 639.75 × 639.75
  4. Step 4: Simplify right side
    258x = 409,280.06
  5. Step 5: Solve for x
    x = 409,280.06/258
  6. Step 6: Final answer
    x = 1,586.36

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Why These Related Problems?

These problems maintain the same ratio (2.48) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.