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Finding the Fourth Proportional to 989.90, 1,366.10 and 640.59

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Solution

The fourth proportional to 989.90, 1,366.10 and 640.59 is: 884.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.90 : 1,366.10 = 640.59 : x
  2. Step 2: Convert to fraction form
    989.90/1,366.10 = 640.59/x
  3. Step 3: Cross multiply
    989.90x = 1,366.10 × 640.59
  4. Step 4: Simplify right side
    989.90x = 875,099.97
  5. Step 5: Solve for x
    x = 875,099.97/989.90
  6. Step 6: Final answer
    x = 884.03

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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.