Finding the Fourth Proportional to 21,128.82, 31,724.37 and 11,787.09

Step by Step Solution

1. Step 1: Write the proportion equation
   21,128.82 : 31,724.37 = 11,787.09 : x
2. Step 2: Convert to fraction form
   21,128.82/31,724.37 = 11,787.09/x
3. Step 3: Cross multiply
   21,128.82x = 31,724.37 × 11,787.09
4. Step 4: Simplify right side
   21,128.82x = 373,938,004.38
5. Step 5: Solve for x
   x = 373,938,004.38/21,128.82
6. Step 6: Final answer
   x = 17,698.01