Finding the Fourth Proportional to 1,380.20, 1,904.40 and 855.92

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.20 : 1,904.40 = 855.92 : x
2. Step 2: Convert to fraction form
   1,380.20/1,904.40 = 855.92/x
3. Step 3: Cross multiply
   1,380.20x = 1,904.40 × 855.92
4. Step 4: Simplify right side
   1,380.20x = 1,630,014.05
5. Step 5: Solve for x
   x = 1,630,014.05/1,380.20
6. Step 6: Final answer
   x = 1,181.00