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Finding the Fourth Proportional to 990.40, 1,366.18 and 641.09

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Solution

The fourth proportional to 990.40, 1,366.18 and 641.09 is: 884.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.40 : 1,366.18 = 641.09 : x
  2. Step 2: Convert to fraction form
    990.40/1,366.18 = 641.09/x
  3. Step 3: Cross multiply
    990.40x = 1,366.18 × 641.09
  4. Step 4: Simplify right side
    990.40x = 875,835.90
  5. Step 5: Solve for x
    x = 875,835.90/990.40
  6. Step 6: Final answer
    x = 884.33

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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.