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Finding the Fourth Proportional to 1,285.21, 1,920.00 and 819.28

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Solution

The fourth proportional to 1,285.21, 1,920.00 and 819.28 is: 1,223.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,285.21 : 1,920.00 = 819.28 : x
  2. Step 2: Convert to fraction form
    1,285.21/1,920.00 = 819.28/x
  3. Step 3: Cross multiply
    1,285.21x = 1,920.00 × 819.28
  4. Step 4: Simplify right side
    1,285.21x = 1,573,003.90
  5. Step 5: Solve for x
    x = 1,573,003.90/1,285.21
  6. Step 6: Final answer
    x = 1,223.93

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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.