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Finding the Third Proportional to 390.75 and 840.75

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Solution

The third proportional to 390.75 and 840.75 is: 1,808.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.75 : 840.75 = 840.75 : x
  2. Step 2: Convert to fraction form
    390.75/840.75 = 840.75/x
  3. Step 3: Cross multiply
    390.75x = 840.75 × 840.75
  4. Step 4: Simplify right side
    390.75x = 706,860.56
  5. Step 5: Solve for x
    x = 706,860.56/390.75
  6. Step 6: Final answer
    x = 1,808.98

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Why These Related Problems?

These problems maintain the same ratio (2.15) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.