Finding the Fourth Proportional to 13,139.18, 18,131.94 and 7,170.90

Step by Step Solution

1. Step 1: Write the proportion equation
   13,139.18 : 18,131.94 = 7,170.90 : x
2. Step 2: Convert to fraction form
   13,139.18/18,131.94 = 7,170.90/x
3. Step 3: Cross multiply
   13,139.18x = 18,131.94 × 7,170.90
4. Step 4: Simplify right side
   13,139.18x = 130,022,328.55
5. Step 5: Solve for x
   x = 130,022,328.55/13,139.18
6. Step 6: Final answer
   x = 9,895.77