Finding the Fourth Proportional to 2,216.61, 3,326.58 and 831.31

Step by Step Solution

1. Step 1: Write the proportion equation
   2,216.61 : 3,326.58 = 831.31 : x
2. Step 2: Convert to fraction form
   2,216.61/3,326.58 = 831.31/x
3. Step 3: Cross multiply
   2,216.61x = 3,326.58 × 831.31
4. Step 4: Simplify right side
   2,216.61x = 2,765,410.90
5. Step 5: Solve for x
   x = 2,765,410.90/2,216.61
6. Step 6: Final answer
   x = 1,247.59