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Finding the Fourth Proportional to 999.99, 1,380.62 and 685.78

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Solution

The fourth proportional to 999.99, 1,380.62 and 685.78 is: 946.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    999.99 : 1,380.62 = 685.78 : x
  2. Step 2: Convert to fraction form
    999.99/1,380.62 = 685.78/x
  3. Step 3: Cross multiply
    999.99x = 1,380.62 × 685.78
  4. Step 4: Simplify right side
    999.99x = 946,801.58
  5. Step 5: Solve for x
    x = 946,801.58/999.99
  6. Step 6: Final answer
    x = 946.81

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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.