Finding the Fourth Proportional to 21,859.89, 30,159.81 and 12,910.56

Step by Step Solution

1. Step 1: Write the proportion equation
   21,859.89 : 30,159.81 = 12,910.56 : x
2. Step 2: Convert to fraction form
   21,859.89/30,159.81 = 12,910.56/x
3. Step 3: Cross multiply
   21,859.89x = 30,159.81 × 12,910.56
4. Step 4: Simplify right side
   21,859.89x = 389,380,036.59
5. Step 5: Solve for x
   x = 389,380,036.59/21,859.89
6. Step 6: Final answer
   x = 17,812.53