Finding the Fourth Proportional to 13,139.89, 18,132.79 and 7,171.60

Step by Step Solution

1. Step 1: Write the proportion equation
   13,139.89 : 18,132.79 = 7,171.60 : x
2. Step 2: Convert to fraction form
   13,139.89/18,132.79 = 7,171.60/x
3. Step 3: Cross multiply
   13,139.89x = 18,132.79 × 7,171.60
4. Step 4: Simplify right side
   13,139.89x = 130,041,088.94
5. Step 5: Solve for x
   x = 130,041,088.94/13,139.89
6. Step 6: Final answer
   x = 9,896.67