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Finding the Fourth Proportional to 990.09, 1,366.47 and 641.39

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Solution

The fourth proportional to 990.09, 1,366.47 and 641.39 is: 885.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.09 : 1,366.47 = 641.39 : x
  2. Step 2: Convert to fraction form
    990.09/1,366.47 = 641.39/x
  3. Step 3: Cross multiply
    990.09x = 1,366.47 × 641.39
  4. Step 4: Simplify right side
    990.09x = 876,433.36
  5. Step 5: Solve for x
    x = 876,433.36/990.09
  6. Step 6: Final answer
    x = 885.21

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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.