Finding the Fourth Proportional to 13,139.50, 18,132.84 and 7,171.72

Step by Step Solution

1. Step 1: Write the proportion equation
   13,139.50 : 18,132.84 = 7,171.72 : x
2. Step 2: Convert to fraction form
   13,139.50/18,132.84 = 7,171.72/x
3. Step 3: Cross multiply
   13,139.50x = 18,132.84 × 7,171.72
4. Step 4: Simplify right side
   13,139.50x = 130,043,651.28
5. Step 5: Solve for x
   x = 130,043,651.28/13,139.50
6. Step 6: Final answer
   x = 9,897.15