Finding the Fourth Proportional to 1,390.92, 2,084.55 and 774.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.92 : 2,084.55 = 774.31 : x
2. Step 2: Convert to fraction form
   1,390.92/2,084.55 = 774.31/x
3. Step 3: Cross multiply
   1,390.92x = 2,084.55 × 774.31
4. Step 4: Simplify right side
   1,390.92x = 1,614,087.91
5. Step 5: Solve for x
   x = 1,614,087.91/1,390.92
6. Step 6: Final answer
   x = 1,160.45