Finding the Fourth Proportional to 1,386.91, 1,913.96 and 789.33

Step by Step Solution

1. Step 1: Write the proportion equation
   1,386.91 : 1,913.96 = 789.33 : x
2. Step 2: Convert to fraction form
   1,386.91/1,913.96 = 789.33/x
3. Step 3: Cross multiply
   1,386.91x = 1,913.96 × 789.33
4. Step 4: Simplify right side
   1,386.91x = 1,510,755.20
5. Step 5: Solve for x
   x = 1,510,755.20/1,386.91
6. Step 6: Final answer
   x = 1,089.29