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Finding the Fourth Proportional to 989.53, 1,365.44 and 640.22

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Solution

The fourth proportional to 989.53, 1,365.44 and 640.22 is: 883.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.53 : 1,365.44 = 640.22 : x
  2. Step 2: Convert to fraction form
    989.53/1,365.44 = 640.22/x
  3. Step 3: Cross multiply
    989.53x = 1,365.44 × 640.22
  4. Step 4: Simplify right side
    989.53x = 874,171.97
  5. Step 5: Solve for x
    x = 874,171.97/989.53
  6. Step 6: Final answer
    x = 883.42

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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.