Finding the Fourth Proportional to 8,112.85, 12,110.59 and 7,128.70

Step by Step Solution

1. Step 1: Write the proportion equation
   8,112.85 : 12,110.59 = 7,128.70 : x
2. Step 2: Convert to fraction form
   8,112.85/12,110.59 = 7,128.70/x
3. Step 3: Cross multiply
   8,112.85x = 12,110.59 × 7,128.70
4. Step 4: Simplify right side
   8,112.85x = 86,332,762.93
5. Step 5: Solve for x
   x = 86,332,762.93/8,112.85
6. Step 6: Final answer
   x = 10,641.48