Finding the Fourth Proportional to 1,379.67, 1,904.12 and 790.21

Step by Step Solution

1. Step 1: Write the proportion equation
   1,379.67 : 1,904.12 = 790.21 : x
2. Step 2: Convert to fraction form
   1,379.67/1,904.12 = 790.21/x
3. Step 3: Cross multiply
   1,379.67x = 1,904.12 × 790.21
4. Step 4: Simplify right side
   1,379.67x = 1,504,654.67
5. Step 5: Solve for x
   x = 1,504,654.67/1,379.67
6. Step 6: Final answer
   x = 1,090.59