Finding the Fourth Proportional to 8,791.68, 12,121.20 and 5,646.72

Step by Step Solution

1. Step 1: Write the proportion equation
   8,791.68 : 12,121.20 = 5,646.72 : x
2. Step 2: Convert to fraction form
   8,791.68/12,121.20 = 5,646.72/x
3. Step 3: Cross multiply
   8,791.68x = 12,121.20 × 5,646.72
4. Step 4: Simplify right side
   8,791.68x = 68,445,022.46
5. Step 5: Solve for x
   x = 68,445,022.46/8,791.68
6. Step 6: Final answer
   x = 7,785.20