Finding the Fourth Proportional to 1,380.18, 1,904.61 and 790.70

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.18 : 1,904.61 = 790.70 : x
2. Step 2: Convert to fraction form
   1,380.18/1,904.61 = 790.70/x
3. Step 3: Cross multiply
   1,380.18x = 1,904.61 × 790.70
4. Step 4: Simplify right side
   1,380.18x = 1,505,975.13
5. Step 5: Solve for x
   x = 1,505,975.13/1,380.18
6. Step 6: Final answer
   x = 1,091.14