Finding the Fourth Proportional to 1,380.06, 1,904.61 and 790.65

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.06 : 1,904.61 = 790.65 : x
2. Step 2: Convert to fraction form
   1,380.06/1,904.61 = 790.65/x
3. Step 3: Cross multiply
   1,380.06x = 1,904.61 × 790.65
4. Step 4: Simplify right side
   1,380.06x = 1,505,879.90
5. Step 5: Solve for x
   x = 1,505,879.90/1,380.06
6. Step 6: Final answer
   x = 1,091.17