Finding the Fourth Proportional to 20,859, 28,785.42 and 12,477.48

Step by Step Solution

1. Step 1: Write the proportion equation
   20,859 : 28,785.42 = 12,477.48 : x
2. Step 2: Convert to fraction form
   20,859/28,785.42 = 12,477.48/x
3. Step 3: Cross multiply
   20,859x = 28,785.42 × 12,477.48
4. Step 4: Simplify right side
   20,859x = 359,169,502.34
5. Step 5: Solve for x
   x = 359,169,502.34/20,859
6. Step 6: Final answer
   x = 17,218.92