Finding the Fourth Proportional to 2,800.20, 3,862.56 and 2,015.31

Step by Step Solution

1. Step 1: Write the proportion equation
   2,800.20 : 3,862.56 = 2,015.31 : x
2. Step 2: Convert to fraction form
   2,800.20/3,862.56 = 2,015.31/x
3. Step 3: Cross multiply
   2,800.20x = 3,862.56 × 2,015.31
4. Step 4: Simplify right side
   2,800.20x = 7,784,255.79
5. Step 5: Solve for x
   x = 7,784,255.79/2,800.20
6. Step 6: Final answer
   x = 2,779.89