Finding the Fourth Proportional to 20,979.57, 31,439.94 and 10,439.58

Step by Step Solution

1. Step 1: Write the proportion equation
   20,979.57 : 31,439.94 = 10,439.58 : x
2. Step 2: Convert to fraction form
   20,979.57/31,439.94 = 10,439.58/x
3. Step 3: Cross multiply
   20,979.57x = 31,439.94 × 10,439.58
4. Step 4: Simplify right side
   20,979.57x = 328,219,768.83
5. Step 5: Solve for x
   x = 328,219,768.83/20,979.57
6. Step 6: Final answer
   x = 15,644.73