Finding the Fourth Proportional to 1,387.32, 1,914.43 and 789.77

Step by Step Solution

1. Step 1: Write the proportion equation
   1,387.32 : 1,914.43 = 789.77 : x
2. Step 2: Convert to fraction form
   1,387.32/1,914.43 = 789.77/x
3. Step 3: Cross multiply
   1,387.32x = 1,914.43 × 789.77
4. Step 4: Simplify right side
   1,387.32x = 1,511,959.38
5. Step 5: Solve for x
   x = 1,511,959.38/1,387.32
6. Step 6: Final answer
   x = 1,089.84