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Finding the Third Proportional to 399 and 685.50

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Solution

The third proportional to 399 and 685.50 is: 1,177.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    399 : 685.50 = 685.50 : x
  2. Step 2: Convert to fraction form
    399/685.50 = 685.50/x
  3. Step 3: Cross multiply
    399x = 685.50 × 685.50
  4. Step 4: Simplify right side
    399x = 469,910.25
  5. Step 5: Solve for x
    x = 469,910.25/399
  6. Step 6: Final answer
    x = 1,177.72

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Why These Related Problems?

These problems maintain the same ratio (1.72) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.