Finding the Fourth Proportional to 1,286.94, 1,776.15 and 789.42

Step by Step Solution

1. Step 1: Write the proportion equation
   1,286.94 : 1,776.15 = 789.42 : x
2. Step 2: Convert to fraction form
   1,286.94/1,776.15 = 789.42/x
3. Step 3: Cross multiply
   1,286.94x = 1,776.15 × 789.42
4. Step 4: Simplify right side
   1,286.94x = 1,402,128.33
5. Step 5: Solve for x
   x = 1,402,128.33/1,286.94
6. Step 6: Final answer
   x = 1,089.51