Finding the Fourth Proportional to 1,139.40, 1,573.02 and 789.48

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.40 : 1,573.02 = 789.48 : x
2. Step 2: Convert to fraction form
   1,139.40/1,573.02 = 789.48/x
3. Step 3: Cross multiply
   1,139.40x = 1,573.02 × 789.48
4. Step 4: Simplify right side
   1,139.40x = 1,241,867.83
5. Step 5: Solve for x
   x = 1,241,867.83/1,139.40
6. Step 6: Final answer
   x = 1,089.93