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Finding the Fourth Proportional to 1,285.71, 1,920.74 and 819.78

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Solution

The fourth proportional to 1,285.71, 1,920.74 and 819.78 is: 1,224.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,285.71 : 1,920.74 = 819.78 : x
  2. Step 2: Convert to fraction form
    1,285.71/1,920.74 = 819.78/x
  3. Step 3: Cross multiply
    1,285.71x = 1,920.74 × 819.78
  4. Step 4: Simplify right side
    1,285.71x = 1,574,584.24
  5. Step 5: Solve for x
    x = 1,574,584.24/1,285.71
  6. Step 6: Final answer
    x = 1,224.68

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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.