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Finding the Fourth Proportional to 739.78, 1,020.90 and 408.20

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Solution

The fourth proportional to 739.78, 1,020.90 and 408.20 is: 563.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    739.78 : 1,020.90 = 408.20 : x
  2. Step 2: Convert to fraction form
    739.78/1,020.90 = 408.20/x
  3. Step 3: Cross multiply
    739.78x = 1,020.90 × 408.20
  4. Step 4: Simplify right side
    739.78x = 416,724.23
  5. Step 5: Solve for x
    x = 416,724.23/739.78
  6. Step 6: Final answer
    x = 563.31

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.