Finding the Fourth Proportional to 21,671.55, 29,908.89 and 12,718.86

Step by Step Solution

1. Step 1: Write the proportion equation
   21,671.55 : 29,908.89 = 12,718.86 : x
2. Step 2: Convert to fraction form
   21,671.55/29,908.89 = 12,718.86/x
3. Step 3: Cross multiply
   21,671.55x = 29,908.89 × 12,718.86
4. Step 4: Simplify right side
   21,671.55x = 380,406,771.53
5. Step 5: Solve for x
   x = 380,406,771.53/21,671.55
6. Step 6: Final answer
   x = 17,553.28