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Finding the Fourth Proportional to 1,287.92, 1,930.88 and 638.15

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Solution

The fourth proportional to 1,287.92, 1,930.88 and 638.15 is: 956.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,287.92 : 1,930.88 = 638.15 : x
  2. Step 2: Convert to fraction form
    1,287.92/1,930.88 = 638.15/x
  3. Step 3: Cross multiply
    1,287.92x = 1,930.88 × 638.15
  4. Step 4: Simplify right side
    1,287.92x = 1,232,183.01
  5. Step 5: Solve for x
    x = 1,232,183.01/1,287.92
  6. Step 6: Final answer
    x = 956.73

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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.