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Finding the Fourth Proportional to 685.20, 1,028.57 and 408.16

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Solution

The fourth proportional to 685.20, 1,028.57 and 408.16 is: 612.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.20 : 1,028.57 = 408.16 : x
  2. Step 2: Convert to fraction form
    685.20/1,028.57 = 408.16/x
  3. Step 3: Cross multiply
    685.20x = 1,028.57 × 408.16
  4. Step 4: Simplify right side
    685.20x = 419,821.13
  5. Step 5: Solve for x
    x = 419,821.13/685.20
  6. Step 6: Final answer
    x = 612.70

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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.