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Finding the Fourth Proportional to 989.42, 1,365.84 and 640.28

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Solution

The fourth proportional to 989.42, 1,365.84 and 640.28 is: 883.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.42 : 1,365.84 = 640.28 : x
  2. Step 2: Convert to fraction form
    989.42/1,365.84 = 640.28/x
  3. Step 3: Cross multiply
    989.42x = 1,365.84 × 640.28
  4. Step 4: Simplify right side
    989.42x = 874,520.04
  5. Step 5: Solve for x
    x = 874,520.04/989.42
  6. Step 6: Final answer
    x = 883.87

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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.