Finding the Fourth Proportional to 1,380.40, 1,905.06 and 791.08

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.40 : 1,905.06 = 791.08 : x
2. Step 2: Convert to fraction form
   1,380.40/1,905.06 = 791.08/x
3. Step 3: Cross multiply
   1,380.40x = 1,905.06 × 791.08
4. Step 4: Simplify right side
   1,380.40x = 1,507,054.86
5. Step 5: Solve for x
   x = 1,507,054.86/1,380.40
6. Step 6: Final answer
   x = 1,091.75