Finding the Fourth Proportional to 1,380.80, 1,902.72 and 1,007.04

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.80 : 1,902.72 = 1,007.04 : x
2. Step 2: Convert to fraction form
   1,380.80/1,902.72 = 1,007.04/x
3. Step 3: Cross multiply
   1,380.80x = 1,902.72 × 1,007.04
4. Step 4: Simplify right side
   1,380.80x = 1,916,115.15
5. Step 5: Solve for x
   x = 1,916,115.15/1,380.80
6. Step 6: Final answer
   x = 1,387.68