Finding the Fourth Proportional to 21,816.71, 30,108.88 and 12,865.96

Step by Step Solution

1. Step 1: Write the proportion equation
   21,816.71 : 30,108.88 = 12,865.96 : x
2. Step 2: Convert to fraction form
   21,816.71/30,108.88 = 12,865.96/x
3. Step 3: Cross multiply
   21,816.71x = 30,108.88 × 12,865.96
4. Step 4: Simplify right side
   21,816.71x = 387,379,645.72
5. Step 5: Solve for x
   x = 387,379,645.72/21,816.71
6. Step 6: Final answer
   x = 17,756.10