Finding the Fourth Proportional to 20,638.98, 30,911.63 and 13,142.57

Step by Step Solution

1. Step 1: Write the proportion equation
   20,638.98 : 30,911.63 = 13,142.57 : x
2. Step 2: Convert to fraction form
   20,638.98/30,911.63 = 13,142.57/x
3. Step 3: Cross multiply
   20,638.98x = 30,911.63 × 13,142.57
4. Step 4: Simplify right side
   20,638.98x = 406,258,040.82
5. Step 5: Solve for x
   x = 406,258,040.82/20,638.98
6. Step 6: Final answer
   x = 19,684.02