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Finding the Fourth Proportional to 678.20, 1,017.40 and 331.55

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Solution

The fourth proportional to 678.20, 1,017.40 and 331.55 is: 497.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.20 : 1,017.40 = 331.55 : x
  2. Step 2: Convert to fraction form
    678.20/1,017.40 = 331.55/x
  3. Step 3: Cross multiply
    678.20x = 1,017.40 × 331.55
  4. Step 4: Simplify right side
    678.20x = 337,318.97
  5. Step 5: Solve for x
    x = 337,318.97/678.20
  6. Step 6: Final answer
    x = 497.37

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.