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Finding the Fourth Proportional to 787.85, 1,086.74 and 489.20

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Solution

The fourth proportional to 787.85, 1,086.74 and 489.20 is: 674.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    787.85 : 1,086.74 = 489.20 : x
  2. Step 2: Convert to fraction form
    787.85/1,086.74 = 489.20/x
  3. Step 3: Cross multiply
    787.85x = 1,086.74 × 489.20
  4. Step 4: Simplify right side
    787.85x = 531,625.33
  5. Step 5: Solve for x
    x = 531,625.33/787.85
  6. Step 6: Final answer
    x = 674.78

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.