Finding the Fourth Proportional to 1,380.63, 1,905.28 and 791.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.63 : 1,905.28 = 791.15 : x
2. Step 2: Convert to fraction form
   1,380.63/1,905.28 = 791.15/x
3. Step 3: Cross multiply
   1,380.63x = 1,905.28 × 791.15
4. Step 4: Simplify right side
   1,380.63x = 1,507,362.27
5. Step 5: Solve for x
   x = 1,507,362.27/1,380.63
6. Step 6: Final answer
   x = 1,091.79