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Finding the Fourth Proportional to 680.10, 1,020.60 and 387.60

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Solution

The fourth proportional to 680.10, 1,020.60 and 387.60 is: 581.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    680.10 : 1,020.60 = 387.60 : x
  2. Step 2: Convert to fraction form
    680.10/1,020.60 = 387.60/x
  3. Step 3: Cross multiply
    680.10x = 1,020.60 × 387.60
  4. Step 4: Simplify right side
    680.10x = 395,584.56
  5. Step 5: Solve for x
    x = 395,584.56/680.10
  6. Step 6: Final answer
    x = 581.66

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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.