Finding the Fourth Proportional to 7,639.56, 10,544.46 and 5,128.74

Step by Step Solution

1. Step 1: Write the proportion equation
   7,639.56 : 10,544.46 = 5,128.74 : x
2. Step 2: Convert to fraction form
   7,639.56/10,544.46 = 5,128.74/x
3. Step 3: Cross multiply
   7,639.56x = 10,544.46 × 5,128.74
4. Step 4: Simplify right side
   7,639.56x = 54,079,793.78
5. Step 5: Solve for x
   x = 54,079,793.78/7,639.56
6. Step 6: Final answer
   x = 7,078.91