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Finding the Fourth Proportional to 862.78, 1,190.64 and 489.64

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Solution

The fourth proportional to 862.78, 1,190.64 and 489.64 is: 675.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    862.78 : 1,190.64 = 489.64 : x
  2. Step 2: Convert to fraction form
    862.78/1,190.64 = 489.64/x
  3. Step 3: Cross multiply
    862.78x = 1,190.64 × 489.64
  4. Step 4: Simplify right side
    862.78x = 582,984.97
  5. Step 5: Solve for x
    x = 582,984.97/862.78
  6. Step 6: Final answer
    x = 675.71

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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.