Finding the Fourth Proportional to 1,380.15, 1,904.16 and 856.35

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.15 : 1,904.16 = 856.35 : x
2. Step 2: Convert to fraction form
   1,380.15/1,904.16 = 856.35/x
3. Step 3: Cross multiply
   1,380.15x = 1,904.16 × 856.35
4. Step 4: Simplify right side
   1,380.15x = 1,630,627.42
5. Step 5: Solve for x
   x = 1,630,627.42/1,380.15
6. Step 6: Final answer
   x = 1,181.49