Finding the Fourth Proportional to 9,120.13, 13,608.78 and 7,939.15

Step by Step Solution

1. Step 1: Write the proportion equation
   9,120.13 : 13,608.78 = 7,939.15 : x
2. Step 2: Convert to fraction form
   9,120.13/13,608.78 = 7,939.15/x
3. Step 3: Cross multiply
   9,120.13x = 13,608.78 × 7,939.15
4. Step 4: Simplify right side
   9,120.13x = 108,042,081.94
5. Step 5: Solve for x
   x = 108,042,081.94/9,120.13
6. Step 6: Final answer
   x = 11,846.55