Finding the Fourth Proportional to 21,745.59, 30,022.16 and 20,405.31

Step by Step Solution

1. Step 1: Write the proportion equation
   21,745.59 : 30,022.16 = 20,405.31 : x
2. Step 2: Convert to fraction form
   21,745.59/30,022.16 = 20,405.31/x
3. Step 3: Cross multiply
   21,745.59x = 30,022.16 × 20,405.31
4. Step 4: Simplify right side
   21,745.59x = 612,611,481.67
5. Step 5: Solve for x
   x = 612,611,481.67/21,745.59
6. Step 6: Final answer
   x = 28,171.76