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Finding the Third Proportional to 389.81 and 811.69

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Solution

The third proportional to 389.81 and 811.69 is: 1,690.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    389.81 : 811.69 = 811.69 : x
  2. Step 2: Convert to fraction form
    389.81/811.69 = 811.69/x
  3. Step 3: Cross multiply
    389.81x = 811.69 × 811.69
  4. Step 4: Simplify right side
    389.81x = 658,836.60
  5. Step 5: Solve for x
    x = 658,836.60/389.81
  6. Step 6: Final answer
    x = 1,690.14

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Why These Related Problems?

These problems maintain the same ratio (2.08) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.