Finding the Fourth Proportional to 1,379.76, 1,904.07 and 790.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,379.76 : 1,904.07 = 790.31 : x
2. Step 2: Convert to fraction form
   1,379.76/1,904.07 = 790.31/x
3. Step 3: Cross multiply
   1,379.76x = 1,904.07 × 790.31
4. Step 4: Simplify right side
   1,379.76x = 1,504,796.04
5. Step 5: Solve for x
   x = 1,504,796.04/1,379.76
6. Step 6: Final answer
   x = 1,090.62