Finding the Fourth Proportional to 20,356.56, 28,085.67 and 12,399.12

Step by Step Solution

1. Step 1: Write the proportion equation
   20,356.56 : 28,085.67 = 12,399.12 : x
2. Step 2: Convert to fraction form
   20,356.56/28,085.67 = 12,399.12/x
3. Step 3: Cross multiply
   20,356.56x = 28,085.67 × 12,399.12
4. Step 4: Simplify right side
   20,356.56x = 348,237,592.61
5. Step 5: Solve for x
   x = 348,237,592.61/20,356.56
6. Step 6: Final answer
   x = 17,106.90