Finding the Fourth Proportional to 2,800.31, 4,199.79 and 1,239.45

Step by Step Solution

1. Step 1: Write the proportion equation
   2,800.31 : 4,199.79 = 1,239.45 : x
2. Step 2: Convert to fraction form
   2,800.31/4,199.79 = 1,239.45/x
3. Step 3: Cross multiply
   2,800.31x = 4,199.79 × 1,239.45
4. Step 4: Simplify right side
   2,800.31x = 5,205,429.72
5. Step 5: Solve for x
   x = 5,205,429.72/2,800.31
6. Step 6: Final answer
   x = 1,858.88