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Finding the Third Proportional to 278.25 and 390.75

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Solution

The third proportional to 278.25 and 390.75 is: 548.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    278.25 : 390.75 = 390.75 : x
  2. Step 2: Convert to fraction form
    278.25/390.75 = 390.75/x
  3. Step 3: Cross multiply
    278.25x = 390.75 × 390.75
  4. Step 4: Simplify right side
    278.25x = 152,685.56
  5. Step 5: Solve for x
    x = 152,685.56/278.25
  6. Step 6: Final answer
    x = 548.74

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Why These Related Problems?

These problems maintain the same ratio (1.40) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.