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Finding the Third Proportional to 389.25 and 688.50

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Solution

The third proportional to 389.25 and 688.50 is: 1,217.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    389.25 : 688.50 = 688.50 : x
  2. Step 2: Convert to fraction form
    389.25/688.50 = 688.50/x
  3. Step 3: Cross multiply
    389.25x = 688.50 × 688.50
  4. Step 4: Simplify right side
    389.25x = 474,032.25
  5. Step 5: Solve for x
    x = 474,032.25/389.25
  6. Step 6: Final answer
    x = 1,217.81

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Why These Related Problems?

These problems maintain the same ratio (1.77) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.