Finding the Fourth Proportional to 21,128.09, 31,690.24 and 6,340.31

Step by Step Solution

1. Step 1: Write the proportion equation
   21,128.09 : 31,690.24 = 6,340.31 : x
2. Step 2: Convert to fraction form
   21,128.09/31,690.24 = 6,340.31/x
3. Step 3: Cross multiply
   21,128.09x = 31,690.24 × 6,340.31
4. Step 4: Simplify right side
   21,128.09x = 200,925,945.57
5. Step 5: Solve for x
   x = 200,925,945.57/21,128.09
6. Step 6: Final answer
   x = 9,509.90