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Finding the Third Proportional to 312.80 and 490.69

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Solution

The third proportional to 312.80 and 490.69 is: 769.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    312.80 : 490.69 = 490.69 : x
  2. Step 2: Convert to fraction form
    312.80/490.69 = 490.69/x
  3. Step 3: Cross multiply
    312.80x = 490.69 × 490.69
  4. Step 4: Simplify right side
    312.80x = 240,774.22
  5. Step 5: Solve for x
    x = 240,774.22/312.80
  6. Step 6: Final answer
    x = 769.75

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Why These Related Problems?

These problems maintain the same ratio (1.57) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.