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Finding the Fourth Proportional to 789.10, 1,086.69 and 640.60

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Solution

The fourth proportional to 789.10, 1,086.69 and 640.60 is: 882.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    789.10 : 1,086.69 = 640.60 : x
  2. Step 2: Convert to fraction form
    789.10/1,086.69 = 640.60/x
  3. Step 3: Cross multiply
    789.10x = 1,086.69 × 640.60
  4. Step 4: Simplify right side
    789.10x = 696,133.61
  5. Step 5: Solve for x
    x = 696,133.61/789.10
  6. Step 6: Final answer
    x = 882.19

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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.