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Finding the Fourth Proportional to 825.91, 1,138.96 and 639.80

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Solution

The fourth proportional to 825.91, 1,138.96 and 639.80 is: 882.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    825.91 : 1,138.96 = 639.80 : x
  2. Step 2: Convert to fraction form
    825.91/1,138.96 = 639.80/x
  3. Step 3: Cross multiply
    825.91x = 1,138.96 × 639.80
  4. Step 4: Simplify right side
    825.91x = 728,706.61
  5. Step 5: Solve for x
    x = 728,706.61/825.91
  6. Step 6: Final answer
    x = 882.31

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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.