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Finding the Fourth Proportional to 685.39, 1,028.42 and 320.09

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Solution

The fourth proportional to 685.39, 1,028.42 and 320.09 is: 480.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.39 : 1,028.42 = 320.09 : x
  2. Step 2: Convert to fraction form
    685.39/1,028.42 = 320.09/x
  3. Step 3: Cross multiply
    685.39x = 1,028.42 × 320.09
  4. Step 4: Simplify right side
    685.39x = 329,186.96
  5. Step 5: Solve for x
    x = 329,186.96/685.39
  6. Step 6: Final answer
    x = 480.29

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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.