Finding the Fourth Proportional to 1,380.25, 1,904.88 and 856.45

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.25 : 1,904.88 = 856.45 : x
2. Step 2: Convert to fraction form
   1,380.25/1,904.88 = 856.45/x
3. Step 3: Cross multiply
   1,380.25x = 1,904.88 × 856.45
4. Step 4: Simplify right side
   1,380.25x = 1,631,434.48
5. Step 5: Solve for x
   x = 1,631,434.48/1,380.25
6. Step 6: Final answer
   x = 1,181.98