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Finding the Third Proportional to 642.50 and 1,285

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Solution

The third proportional to 642.50 and 1,285 is: 2,570

Step by Step Solution

  1. Step 1: Write the proportion equation
    642.50 : 1,285 = 1,285 : x
  2. Step 2: Convert to fraction form
    642.50/1,285 = 1,285/x
  3. Step 3: Cross multiply
    642.50x = 1,285 × 1,285
  4. Step 4: Simplify right side
    642.50x = 1,651,225
  5. Step 5: Solve for x
    x = 1,651,225/642.50
  6. Step 6: Final answer
    x = 2,570

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Why These Related Problems?

These problems maintain the same ratio (2) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.