Finding the Fourth Proportional to 1,139.61, 1,573.25 and 789.69

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.61 : 1,573.25 = 789.69 : x
2. Step 2: Convert to fraction form
   1,139.61/1,573.25 = 789.69/x
3. Step 3: Cross multiply
   1,139.61x = 1,573.25 × 789.69
4. Step 4: Simplify right side
   1,139.61x = 1,242,375.84
5. Step 5: Solve for x
   x = 1,242,375.84/1,139.61
6. Step 6: Final answer
   x = 1,090.18