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Finding the Third Proportional to 643.50 and 1,390.50

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Solution

The third proportional to 643.50 and 1,390.50 is: 3,004.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.50 : 1,390.50 = 1,390.50 : x
  2. Step 2: Convert to fraction form
    643.50/1,390.50 = 1,390.50/x
  3. Step 3: Cross multiply
    643.50x = 1,390.50 × 1,390.50
  4. Step 4: Simplify right side
    643.50x = 1,933,490.25
  5. Step 5: Solve for x
    x = 1,933,490.25/643.50
  6. Step 6: Final answer
    x = 3,004.65

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Why These Related Problems?

These problems maintain the same ratio (2.16) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.