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Finding the Fourth Proportional to 989.84, 1,366.44 and 640.64

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Solution

The fourth proportional to 989.84, 1,366.44 and 640.64 is: 884.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.84 : 1,366.44 = 640.64 : x
  2. Step 2: Convert to fraction form
    989.84/1,366.44 = 640.64/x
  3. Step 3: Cross multiply
    989.84x = 1,366.44 × 640.64
  4. Step 4: Simplify right side
    989.84x = 875,396.12
  5. Step 5: Solve for x
    x = 875,396.12/989.84
  6. Step 6: Final answer
    x = 884.38

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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.