Finding the Fourth Proportional to 2,128.72, 3,186.26 and 1,139.07

Step by Step Solution

1. Step 1: Write the proportion equation
   2,128.72 : 3,186.26 = 1,139.07 : x
2. Step 2: Convert to fraction form
   2,128.72/3,186.26 = 1,139.07/x
3. Step 3: Cross multiply
   2,128.72x = 3,186.26 × 1,139.07
4. Step 4: Simplify right side
   2,128.72x = 3,629,373.18
5. Step 5: Solve for x
   x = 3,629,373.18/2,128.72
6. Step 6: Final answer
   x = 1,704.96