Finding the Fourth Proportional to 21,399, 29,530.73 and 11,967.57

Step by Step Solution

1. Step 1: Write the proportion equation
   21,399 : 29,530.73 = 11,967.57 : x
2. Step 2: Convert to fraction form
   21,399/29,530.73 = 11,967.57/x
3. Step 3: Cross multiply
   21,399x = 29,530.73 × 11,967.57
4. Step 4: Simplify right side
   21,399x = 353,411,018.59
5. Step 5: Solve for x
   x = 353,411,018.59/21,399
6. Step 6: Final answer
   x = 16,515.31