Finding the Fourth Proportional to 21,155.72, 31,735.17 and 7,115.78

Step by Step Solution

1. Step 1: Write the proportion equation
   21,155.72 : 31,735.17 = 7,115.78 : x
2. Step 2: Convert to fraction form
   21,155.72/31,735.17 = 7,115.78/x
3. Step 3: Cross multiply
   21,155.72x = 31,735.17 × 7,115.78
4. Step 4: Simplify right side
   21,155.72x = 225,820,567.32
5. Step 5: Solve for x
   x = 225,820,567.32/21,155.72
6. Step 6: Final answer
   x = 10,674.21