Finding the Fourth Proportional to 22,689.35, 31,315.42 and 13,128.11

Step by Step Solution

1. Step 1: Write the proportion equation
   22,689.35 : 31,315.42 = 13,128.11 : x
2. Step 2: Convert to fraction form
   22,689.35/31,315.42 = 13,128.11/x
3. Step 3: Cross multiply
   22,689.35x = 31,315.42 × 13,128.11
4. Step 4: Simplify right side
   22,689.35x = 411,112,373.15
5. Step 5: Solve for x
   x = 411,112,373.15/22,689.35
6. Step 6: Final answer
   x = 18,119.18