Finding the Fourth Proportional to 21,338.05, 29,451.78 and 12,961.57

Step by Step Solution

1. Step 1: Write the proportion equation
   21,338.05 : 29,451.78 = 12,961.57 : x
2. Step 2: Convert to fraction form
   21,338.05/29,451.78 = 12,961.57/x
3. Step 3: Cross multiply
   21,338.05x = 29,451.78 × 12,961.57
4. Step 4: Simplify right side
   21,338.05x = 381,741,096.03
5. Step 5: Solve for x
   x = 381,741,096.03/21,338.05
6. Step 6: Final answer
   x = 17,890.16