Finding the Fourth Proportional to 1,379.78, 1,904.14 and 790.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,379.78 : 1,904.14 = 790.50 : x
2. Step 2: Convert to fraction form
   1,379.78/1,904.14 = 790.50/x
3. Step 3: Cross multiply
   1,379.78x = 1,904.14 × 790.50
4. Step 4: Simplify right side
   1,379.78x = 1,505,222.67
5. Step 5: Solve for x
   x = 1,505,222.67/1,379.78
6. Step 6: Final answer
   x = 1,090.91