Finding the Fourth Proportional to 8,781.30, 12,129.57 and 7,113.78

Step by Step Solution

1. Step 1: Write the proportion equation
   8,781.30 : 12,129.57 = 7,113.78 : x
2. Step 2: Convert to fraction form
   8,781.30/12,129.57 = 7,113.78/x
3. Step 3: Cross multiply
   8,781.30x = 12,129.57 × 7,113.78
4. Step 4: Simplify right side
   8,781.30x = 86,287,092.47
5. Step 5: Solve for x
   x = 86,287,092.47/8,781.30
6. Step 6: Final answer
   x = 9,826.23