Finding the Fourth Proportional to 1,380.80, 1,905.83 and 850.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.80 : 1,905.83 = 850.15 : x
2. Step 2: Convert to fraction form
   1,380.80/1,905.83 = 850.15/x
3. Step 3: Cross multiply
   1,380.80x = 1,905.83 × 850.15
4. Step 4: Simplify right side
   1,380.80x = 1,620,227.59
5. Step 5: Solve for x
   x = 1,620,227.59/1,380.80
6. Step 6: Final answer
   x = 1,173.40