Finding the Fourth Proportional to 13,139.24, 18,131.70 and 7,831.30

Step by Step Solution

1. Step 1: Write the proportion equation
   13,139.24 : 18,131.70 = 7,831.30 : x
2. Step 2: Convert to fraction form
   13,139.24/18,131.70 = 7,831.30/x
3. Step 3: Cross multiply
   13,139.24x = 18,131.70 × 7,831.30
4. Step 4: Simplify right side
   13,139.24x = 141,994,782.21
5. Step 5: Solve for x
   x = 141,994,782.21/13,139.24
6. Step 6: Final answer
   x = 10,806.93