Finding the Fourth Proportional to 1,287.41, 1,775.89 and 789.86

Step by Step Solution

1. Step 1: Write the proportion equation
   1,287.41 : 1,775.89 = 789.86 : x
2. Step 2: Convert to fraction form
   1,287.41/1,775.89 = 789.86/x
3. Step 3: Cross multiply
   1,287.41x = 1,775.89 × 789.86
4. Step 4: Simplify right side
   1,287.41x = 1,402,706.94
5. Step 5: Solve for x
   x = 1,402,706.94/1,287.41
6. Step 6: Final answer
   x = 1,089.56