Finding the Fourth Proportional to 13,109.31, 17,989.10 and 11,921.31

Step by Step Solution

1. Step 1: Write the proportion equation
   13,109.31 : 17,989.10 = 11,921.31 : x
2. Step 2: Convert to fraction form
   13,109.31/17,989.10 = 11,921.31/x
3. Step 3: Cross multiply
   13,109.31x = 17,989.10 × 11,921.31
4. Step 4: Simplify right side
   13,109.31x = 214,453,578.11
5. Step 5: Solve for x
   x = 214,453,578.11/13,109.31
6. Step 6: Final answer
   x = 16,358.88