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Finding the Fourth Proportional to 989.32, 1,365.28 and 640.61

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Solution

The fourth proportional to 989.32, 1,365.28 and 640.61 is: 884.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.32 : 1,365.28 = 640.61 : x
  2. Step 2: Convert to fraction form
    989.32/1,365.28 = 640.61/x
  3. Step 3: Cross multiply
    989.32x = 1,365.28 × 640.61
  4. Step 4: Simplify right side
    989.32x = 874,608.82
  5. Step 5: Solve for x
    x = 874,608.82/989.32
  6. Step 6: Final answer
    x = 884.05

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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.