Finding the Fourth Proportional to 1,391.30, 2,081.55 and 905.30

Step by Step Solution

1. Step 1: Write the proportion equation
   1,391.30 : 2,081.55 = 905.30 : x
2. Step 2: Convert to fraction form
   1,391.30/2,081.55 = 905.30/x
3. Step 3: Cross multiply
   1,391.30x = 2,081.55 × 905.30
4. Step 4: Simplify right side
   1,391.30x = 1,884,427.22
5. Step 5: Solve for x
   x = 1,884,427.22/1,391.30
6. Step 6: Final answer
   x = 1,354.44