Finding the Fourth Proportional to 1,379.69, 1,903.98 and 790.21

Step by Step Solution

1. Step 1: Write the proportion equation
   1,379.69 : 1,903.98 = 790.21 : x
2. Step 2: Convert to fraction form
   1,379.69/1,903.98 = 790.21/x
3. Step 3: Cross multiply
   1,379.69x = 1,903.98 × 790.21
4. Step 4: Simplify right side
   1,379.69x = 1,504,544.04
5. Step 5: Solve for x
   x = 1,504,544.04/1,379.69
6. Step 6: Final answer
   x = 1,090.49