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Finding the Fourth Proportional to 990, 1,366.21 and 641.30

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Solution

The fourth proportional to 990, 1,366.21 and 641.30 is: 884.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    990 : 1,366.21 = 641.30 : x
  2. Step 2: Convert to fraction form
    990/1,366.21 = 641.30/x
  3. Step 3: Cross multiply
    990x = 1,366.21 × 641.30
  4. Step 4: Simplify right side
    990x = 876,144.44
  5. Step 5: Solve for x
    x = 876,144.44/990
  6. Step 6: Final answer
    x = 884.99

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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.