Finding the Fourth Proportional to 2,587.21, 3,879.63 and 831.89

Step by Step Solution

1. Step 1: Write the proportion equation
   2,587.21 : 3,879.63 = 831.89 : x
2. Step 2: Convert to fraction form
   2,587.21/3,879.63 = 831.89/x
3. Step 3: Cross multiply
   2,587.21x = 3,879.63 × 831.89
4. Step 4: Simplify right side
   2,587.21x = 3,227,441.51
5. Step 5: Solve for x
   x = 3,227,441.51/2,587.21
6. Step 6: Final answer
   x = 1,247.46