Finding the Fourth Proportional to 21,242.72, 29,307.12 and 12,856.16

Step by Step Solution

1. Step 1: Write the proportion equation
   21,242.72 : 29,307.12 = 12,856.16 : x
2. Step 2: Convert to fraction form
   21,242.72/29,307.12 = 12,856.16/x
3. Step 3: Cross multiply
   21,242.72x = 29,307.12 × 12,856.16
4. Step 4: Simplify right side
   21,242.72x = 376,777,023.86
5. Step 5: Solve for x
   x = 376,777,023.86/21,242.72
6. Step 6: Final answer
   x = 17,736.76