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Finding the Fourth Proportional to 680.50, 1,020.96 and 391.78

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Solution

The fourth proportional to 680.50, 1,020.96 and 391.78 is: 587.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    680.50 : 1,020.96 = 391.78 : x
  2. Step 2: Convert to fraction form
    680.50/1,020.96 = 391.78/x
  3. Step 3: Cross multiply
    680.50x = 1,020.96 × 391.78
  4. Step 4: Simplify right side
    680.50x = 399,991.71
  5. Step 5: Solve for x
    x = 399,991.71/680.50
  6. Step 6: Final answer
    x = 587.79

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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.