Finding the Fourth Proportional to 21,377.92, 29,499.52 and 12,878.72

Step by Step Solution

1. Step 1: Write the proportion equation
   21,377.92 : 29,499.52 = 12,878.72 : x
2. Step 2: Convert to fraction form
   21,377.92/29,499.52 = 12,878.72/x
3. Step 3: Cross multiply
   21,377.92x = 29,499.52 × 12,878.72
4. Step 4: Simplify right side
   21,377.92x = 379,916,058.21
5. Step 5: Solve for x
   x = 379,916,058.21/21,377.92
6. Step 6: Final answer
   x = 17,771.42