Finding the Fourth Proportional to 13,105.79, 18,086.31 and 7,137.78

Step by Step Solution

1. Step 1: Write the proportion equation
   13,105.79 : 18,086.31 = 7,137.78 : x
2. Step 2: Convert to fraction form
   13,105.79/18,086.31 = 7,137.78/x
3. Step 3: Cross multiply
   13,105.79x = 18,086.31 × 7,137.78
4. Step 4: Simplify right side
   13,105.79x = 129,096,101.79
5. Step 5: Solve for x
   x = 129,096,101.79/13,105.79
6. Step 6: Final answer
   x = 9,850.31