Finding the Fourth Proportional to 1,380.36, 1,904.24 and 790.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.36 : 1,904.24 = 790.55 : x
2. Step 2: Convert to fraction form
   1,380.36/1,904.24 = 790.55/x
3. Step 3: Cross multiply
   1,380.36x = 1,904.24 × 790.55
4. Step 4: Simplify right side
   1,380.36x = 1,505,403.67
5. Step 5: Solve for x
   x = 1,505,403.67/1,380.36
6. Step 6: Final answer
   x = 1,090.59