Finding the Fourth Proportional to 1,139.37, 1,708.42 and 728.25

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.37 : 1,708.42 = 728.25 : x
2. Step 2: Convert to fraction form
   1,139.37/1,708.42 = 728.25/x
3. Step 3: Cross multiply
   1,139.37x = 1,708.42 × 728.25
4. Step 4: Simplify right side
   1,139.37x = 1,244,156.87
5. Step 5: Solve for x
   x = 1,244,156.87/1,139.37
6. Step 6: Final answer
   x = 1,091.97