Finding the Fourth Proportional to 8,113.35, 12,111.34 and 7,129.20

Step by Step Solution

1. Step 1: Write the proportion equation
   8,113.35 : 12,111.34 = 7,129.20 : x
2. Step 2: Convert to fraction form
   8,113.35/12,111.34 = 7,129.20/x
3. Step 3: Cross multiply
   8,113.35x = 12,111.34 × 7,129.20
4. Step 4: Simplify right side
   8,113.35x = 86,344,129.48
5. Step 5: Solve for x
   x = 86,344,129.48/8,113.35
6. Step 6: Final answer
   x = 10,642.23