Finding the Fourth Proportional to 2,680.47, 4,020.19 and 831.31

Step by Step Solution

1. Step 1: Write the proportion equation
   2,680.47 : 4,020.19 = 831.31 : x
2. Step 2: Convert to fraction form
   2,680.47/4,020.19 = 831.31/x
3. Step 3: Cross multiply
   2,680.47x = 4,020.19 × 831.31
4. Step 4: Simplify right side
   2,680.47x = 3,342,024.15
5. Step 5: Solve for x
   x = 3,342,024.15/2,680.47
6. Step 6: Final answer
   x = 1,246.81