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Finding the Third Proportional to 639.50 and 858.75

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Solution

The third proportional to 639.50 and 858.75 is: 1,153.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.50 : 858.75 = 858.75 : x
  2. Step 2: Convert to fraction form
    639.50/858.75 = 858.75/x
  3. Step 3: Cross multiply
    639.50x = 858.75 × 858.75
  4. Step 4: Simplify right side
    639.50x = 737,451.56
  5. Step 5: Solve for x
    x = 737,451.56/639.50
  6. Step 6: Final answer
    x = 1,153.17

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Why These Related Problems?

These problems maintain the same ratio (1.34) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.