Finding the Fourth Proportional to 13,139.90, 18,132.72 and 7,171.64

Step by Step Solution

1. Step 1: Write the proportion equation
   13,139.90 : 18,132.72 = 7,171.64 : x
2. Step 2: Convert to fraction form
   13,139.90/18,132.72 = 7,171.64/x
3. Step 3: Cross multiply
   13,139.90x = 18,132.72 × 7,171.64
4. Step 4: Simplify right side
   13,139.90x = 130,041,340.06
5. Step 5: Solve for x
   x = 130,041,340.06/13,139.90
6. Step 6: Final answer
   x = 9,896.68