Finding the Fourth Proportional to 20,900.30, 31,337.69 and 8,878.28

Step by Step Solution

1. Step 1: Write the proportion equation
   20,900.30 : 31,337.69 = 8,878.28 : x
2. Step 2: Convert to fraction form
   20,900.30/31,337.69 = 8,878.28/x
3. Step 3: Cross multiply
   20,900.30x = 31,337.69 × 8,878.28
4. Step 4: Simplify right side
   20,900.30x = 278,224,585.29
5. Step 5: Solve for x
   x = 278,224,585.29/20,900.30
6. Step 6: Final answer
   x = 13,311.99