Finding the Fourth Proportional to 1,286.81, 1,774.89 and 789.69

Step by Step Solution

1. Step 1: Write the proportion equation
   1,286.81 : 1,774.89 = 789.69 : x
2. Step 2: Convert to fraction form
   1,286.81/1,774.89 = 789.69/x
3. Step 3: Cross multiply
   1,286.81x = 1,774.89 × 789.69
4. Step 4: Simplify right side
   1,286.81x = 1,401,600.06
5. Step 5: Solve for x
   x = 1,401,600.06/1,286.81
6. Step 6: Final answer
   x = 1,089.21