Finding the Fourth Proportional to 21,243.72, 29,308.50 and 12,857.16

Step by Step Solution

1. Step 1: Write the proportion equation
   21,243.72 : 29,308.50 = 12,857.16 : x
2. Step 2: Convert to fraction form
   21,243.72/29,308.50 = 12,857.16/x
3. Step 3: Cross multiply
   21,243.72x = 29,308.50 × 12,857.16
4. Step 4: Simplify right side
   21,243.72x = 376,824,073.86
5. Step 5: Solve for x
   x = 376,824,073.86/21,243.72
6. Step 6: Final answer
   x = 17,738.14