Finding the Fourth Proportional to 3,711.57, 5,121.78 and 2,139.57

Step by Step Solution

1. Step 1: Write the proportion equation
   3,711.57 : 5,121.78 = 2,139.57 : x
2. Step 2: Convert to fraction form
   3,711.57/5,121.78 = 2,139.57/x
3. Step 3: Cross multiply
   3,711.57x = 5,121.78 × 2,139.57
4. Step 4: Simplify right side
   3,711.57x = 10,958,406.83
5. Step 5: Solve for x
   x = 10,958,406.83/3,711.57
6. Step 6: Final answer
   x = 2,952.50