Finding the Fourth Proportional to 1,139.92, 1,574.78 and 1,131.28

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.92 : 1,574.78 = 1,131.28 : x
2. Step 2: Convert to fraction form
   1,139.92/1,574.78 = 1,131.28/x
3. Step 3: Cross multiply
   1,139.92x = 1,574.78 × 1,131.28
4. Step 4: Simplify right side
   1,139.92x = 1,781,517.12
5. Step 5: Solve for x
   x = 1,781,517.12/1,139.92
6. Step 6: Final answer
   x = 1,562.84