Finding the Fourth Proportional to 6,891.12, 9,507.60 and 3,906.72

Step by Step Solution

1. Step 1: Write the proportion equation
   6,891.12 : 9,507.60 = 3,906.72 : x
2. Step 2: Convert to fraction form
   6,891.12/9,507.60 = 3,906.72/x
3. Step 3: Cross multiply
   6,891.12x = 9,507.60 × 3,906.72
4. Step 4: Simplify right side
   6,891.12x = 37,143,531.07
5. Step 5: Solve for x
   x = 37,143,531.07/6,891.12
6. Step 6: Final answer
   x = 5,390.06