Finding the Fourth Proportional to 21,061.82, 31,592.13 and 8,578.76

Step by Step Solution

1. Step 1: Write the proportion equation
   21,061.82 : 31,592.13 = 8,578.76 : x
2. Step 2: Convert to fraction form
   21,061.82/31,592.13 = 8,578.76/x
3. Step 3: Cross multiply
   21,061.82x = 31,592.13 × 8,578.76
4. Step 4: Simplify right side
   21,061.82x = 271,021,380.14
5. Step 5: Solve for x
   x = 271,021,380.14/21,061.82
6. Step 6: Final answer
   x = 12,867.90