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Finding the Fourth Proportional to 1,331.92, 1,998.20 and 638.39

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Solution

The fourth proportional to 1,331.92, 1,998.20 and 638.39 is: 957.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,331.92 : 1,998.20 = 638.39 : x
  2. Step 2: Convert to fraction form
    1,331.92/1,998.20 = 638.39/x
  3. Step 3: Cross multiply
    1,331.92x = 1,998.20 × 638.39
  4. Step 4: Simplify right side
    1,331.92x = 1,275,630.90
  5. Step 5: Solve for x
    x = 1,275,630.90/1,331.92
  6. Step 6: Final answer
    x = 957.74

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.