Finding the Fourth Proportional to 13,428.38, 20,139.54 and 5,105.42

Step by Step Solution

1. Step 1: Write the proportion equation
   13,428.38 : 20,139.54 = 5,105.42 : x
2. Step 2: Convert to fraction form
   13,428.38/20,139.54 = 5,105.42/x
3. Step 3: Cross multiply
   13,428.38x = 20,139.54 × 5,105.42
4. Step 4: Simplify right side
   13,428.38x = 102,820,810.31
5. Step 5: Solve for x
   x = 102,820,810.31/13,428.38
6. Step 6: Final answer
   x = 7,656.98