Finding the Fourth Proportional to 20,788.09, 31,186.20 and 7,640.56

Step by Step Solution

1. Step 1: Write the proportion equation
   20,788.09 : 31,186.20 = 7,640.56 : x
2. Step 2: Convert to fraction form
   20,788.09/31,186.20 = 7,640.56/x
3. Step 3: Cross multiply
   20,788.09x = 31,186.20 × 7,640.56
4. Step 4: Simplify right side
   20,788.09x = 238,280,032.27
5. Step 5: Solve for x
   x = 238,280,032.27/20,788.09
6. Step 6: Final answer
   x = 11,462.33