Finding the Fourth Proportional to 1,387.09, 1,914.18 and 789.59

Step by Step Solution

1. Step 1: Write the proportion equation
   1,387.09 : 1,914.18 = 789.59 : x
2. Step 2: Convert to fraction form
   1,387.09/1,914.18 = 789.59/x
3. Step 3: Cross multiply
   1,387.09x = 1,914.18 × 789.59
4. Step 4: Simplify right side
   1,387.09x = 1,511,417.39
5. Step 5: Solve for x
   x = 1,511,417.39/1,387.09
6. Step 6: Final answer
   x = 1,089.63