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Finding the Fourth Proportional to 989.97, 1,478.94 and 640.46

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Solution

The fourth proportional to 989.97, 1,478.94 and 640.46 is: 956.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.97 : 1,478.94 = 640.46 : x
  2. Step 2: Convert to fraction form
    989.97/1,478.94 = 640.46/x
  3. Step 3: Cross multiply
    989.97x = 1,478.94 × 640.46
  4. Step 4: Simplify right side
    989.97x = 947,194.52
  5. Step 5: Solve for x
    x = 947,194.52/989.97
  6. Step 6: Final answer
    x = 956.79

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.