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Finding the Fourth Proportional to 685.63, 1,028.90 and 320.43

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Solution

The fourth proportional to 685.63, 1,028.90 and 320.43 is: 480.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.63 : 1,028.90 = 320.43 : x
  2. Step 2: Convert to fraction form
    685.63/1,028.90 = 320.43/x
  3. Step 3: Cross multiply
    685.63x = 1,028.90 × 320.43
  4. Step 4: Simplify right side
    685.63x = 329,690.43
  5. Step 5: Solve for x
    x = 329,690.43/685.63
  6. Step 6: Final answer
    x = 480.86

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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.