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Finding the Third Proportional to 390.84 and 853.78

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Solution

The third proportional to 390.84 and 853.78 is: 1,865.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.84 : 853.78 = 853.78 : x
  2. Step 2: Convert to fraction form
    390.84/853.78 = 853.78/x
  3. Step 3: Cross multiply
    390.84x = 853.78 × 853.78
  4. Step 4: Simplify right side
    390.84x = 728,942.42
  5. Step 5: Solve for x
    x = 728,942.42/390.84
  6. Step 6: Final answer
    x = 1,865.05

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Why These Related Problems?

These problems maintain the same ratio (2.18) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.