Finding the Fourth Proportional to 2,485.74, 3,728.20 and 819.89

Step by Step Solution

1. Step 1: Write the proportion equation
   2,485.74 : 3,728.20 = 819.89 : x
2. Step 2: Convert to fraction form
   2,485.74/3,728.20 = 819.89/x
3. Step 3: Cross multiply
   2,485.74x = 3,728.20 × 819.89
4. Step 4: Simplify right side
   2,485.74x = 3,056,713.90
5. Step 5: Solve for x
   x = 3,056,713.90/2,485.74
6. Step 6: Final answer
   x = 1,229.70