Finding the Fourth Proportional to 20,508.56, 30,777.84 and 13,131.12

Step by Step Solution

1. Step 1: Write the proportion equation
   20,508.56 : 30,777.84 = 13,131.12 : x
2. Step 2: Convert to fraction form
   20,508.56/30,777.84 = 13,131.12/x
3. Step 3: Cross multiply
   20,508.56x = 30,777.84 × 13,131.12
4. Step 4: Simplify right side
   20,508.56x = 404,147,510.38
5. Step 5: Solve for x
   x = 404,147,510.38/20,508.56
6. Step 6: Final answer
   x = 19,706.28