Finding the Fourth Proportional to 5,105.72, 7,652.43 and 2,639.21

Step by Step Solution

1. Step 1: Write the proportion equation
   5,105.72 : 7,652.43 = 2,639.21 : x
2. Step 2: Convert to fraction form
   5,105.72/7,652.43 = 2,639.21/x
3. Step 3: Cross multiply
   5,105.72x = 7,652.43 × 2,639.21
4. Step 4: Simplify right side
   5,105.72x = 20,196,369.78
5. Step 5: Solve for x
   x = 20,196,369.78/5,105.72
6. Step 6: Final answer
   x = 3,955.64