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Finding the Fourth Proportional to 689.20, 1,033.80 and 620.80

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Solution

The fourth proportional to 689.20, 1,033.80 and 620.80 is: 931.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    689.20 : 1,033.80 = 620.80 : x
  2. Step 2: Convert to fraction form
    689.20/1,033.80 = 620.80/x
  3. Step 3: Cross multiply
    689.20x = 1,033.80 × 620.80
  4. Step 4: Simplify right side
    689.20x = 641,783.04
  5. Step 5: Solve for x
    x = 641,783.04/689.20
  6. Step 6: Final answer
    x = 931.20

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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.