Finding the Fourth Proportional to 20,789.37, 31,164.61 and 7,638.21

Step by Step Solution

1. Step 1: Write the proportion equation
   20,789.37 : 31,164.61 = 7,638.21 : x
2. Step 2: Convert to fraction form
   20,789.37/31,164.61 = 7,638.21/x
3. Step 3: Cross multiply
   20,789.37x = 31,164.61 × 7,638.21
4. Step 4: Simplify right side
   20,789.37x = 238,041,835.75
5. Step 5: Solve for x
   x = 238,041,835.75/20,789.37
6. Step 6: Final answer
   x = 11,450.17