Finding the Fourth Proportional to 2,620.85, 3,931.37 and 865.89

Step by Step Solution

1. Step 1: Write the proportion equation
   2,620.85 : 3,931.37 = 865.89 : x
2. Step 2: Convert to fraction form
   2,620.85/3,931.37 = 865.89/x
3. Step 3: Cross multiply
   2,620.85x = 3,931.37 × 865.89
4. Step 4: Simplify right side
   2,620.85x = 3,404,129.64
5. Step 5: Solve for x
   x = 3,404,129.64/2,620.85
6. Step 6: Final answer
   x = 1,298.87