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Finding the Fourth Proportional to 685.31, 1,028.11 and 198.40

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Solution

The fourth proportional to 685.31, 1,028.11 and 198.40 is: 297.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.31 : 1,028.11 = 198.40 : x
  2. Step 2: Convert to fraction form
    685.31/1,028.11 = 198.40/x
  3. Step 3: Cross multiply
    685.31x = 1,028.11 × 198.40
  4. Step 4: Simplify right side
    685.31x = 203,972.38
  5. Step 5: Solve for x
    x = 203,972.38/685.31
  6. Step 6: Final answer
    x = 297.64

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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.