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Finding the Third Proportional to 642.25 and 909.25

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Solution

The third proportional to 642.25 and 909.25 is: 1,287.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    642.25 : 909.25 = 909.25 : x
  2. Step 2: Convert to fraction form
    642.25/909.25 = 909.25/x
  3. Step 3: Cross multiply
    642.25x = 909.25 × 909.25
  4. Step 4: Simplify right side
    642.25x = 826,735.56
  5. Step 5: Solve for x
    x = 826,735.56/642.25
  6. Step 6: Final answer
    x = 1,287.25

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Why These Related Problems?

These problems maintain the same ratio (1.42) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.