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Finding the Fourth Proportional to 989.45, 1,365.44 and 640.74

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Solution

The fourth proportional to 989.45, 1,365.44 and 640.74 is: 884.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.45 : 1,365.44 = 640.74 : x
  2. Step 2: Convert to fraction form
    989.45/1,365.44 = 640.74/x
  3. Step 3: Cross multiply
    989.45x = 1,365.44 × 640.74
  4. Step 4: Simplify right side
    989.45x = 874,888.82
  5. Step 5: Solve for x
    x = 874,888.82/989.45
  6. Step 6: Final answer
    x = 884.22

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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.