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Finding the Fourth Proportional to 989.92, 1,366.68 and 641.26

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Solution

The fourth proportional to 989.92, 1,366.68 and 641.26 is: 885.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.92 : 1,366.68 = 641.26 : x
  2. Step 2: Convert to fraction form
    989.92/1,366.68 = 641.26/x
  3. Step 3: Cross multiply
    989.92x = 1,366.68 × 641.26
  4. Step 4: Simplify right side
    989.92x = 876,397.22
  5. Step 5: Solve for x
    x = 876,397.22/989.92
  6. Step 6: Final answer
    x = 885.32

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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.