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Finding the Third Proportional to 643.78 and 1,378.69

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Solution

The third proportional to 643.78 and 1,378.69 is: 2,952.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.78 : 1,378.69 = 1,378.69 : x
  2. Step 2: Convert to fraction form
    643.78/1,378.69 = 1,378.69/x
  3. Step 3: Cross multiply
    643.78x = 1,378.69 × 1,378.69
  4. Step 4: Simplify right side
    643.78x = 1,900,779.22
  5. Step 5: Solve for x
    x = 1,900,779.22/643.78
  6. Step 6: Final answer
    x = 2,952.52

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Why These Related Problems?

These problems maintain the same ratio (2.14) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.