Finding the Fourth Proportional to 9,109.69, 13,679.73 and 8,427.78

Step by Step Solution

1. Step 1: Write the proportion equation
   9,109.69 : 13,679.73 = 8,427.78 : x
2. Step 2: Convert to fraction form
   9,109.69/13,679.73 = 8,427.78/x
3. Step 3: Cross multiply
   9,109.69x = 13,679.73 × 8,427.78
4. Step 4: Simplify right side
   9,109.69x = 115,289,754.90
5. Step 5: Solve for x
   x = 115,289,754.90/9,109.69
6. Step 6: Final answer
   x = 12,655.73