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Finding the Fourth Proportional to 999, 1,378.98 and 667.31

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Solution

The fourth proportional to 999, 1,378.98 and 667.31 is: 921.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    999 : 1,378.98 = 667.31 : x
  2. Step 2: Convert to fraction form
    999/1,378.98 = 667.31/x
  3. Step 3: Cross multiply
    999x = 1,378.98 × 667.31
  4. Step 4: Simplify right side
    999x = 920,200.25
  5. Step 5: Solve for x
    x = 920,200.25/999
  6. Step 6: Final answer
    x = 921.12

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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.