Finding the Fourth Proportional to 13,906.71, 20,853.82 and 8,287.02

Step by Step Solution

1. Step 1: Write the proportion equation
   13,906.71 : 20,853.82 = 8,287.02 : x
2. Step 2: Convert to fraction form
   13,906.71/20,853.82 = 8,287.02/x
3. Step 3: Cross multiply
   13,906.71x = 20,853.82 × 8,287.02
4. Step 4: Simplify right side
   13,906.71x = 172,816,023.42
5. Step 5: Solve for x
   x = 172,816,023.42/13,906.71
6. Step 6: Final answer
   x = 12,426.81