Finding the Fourth Proportional to 1,380.24, 1,904.43 and 1,007.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.24 : 1,904.43 = 1,007.31 : x
2. Step 2: Convert to fraction form
   1,380.24/1,904.43 = 1,007.31/x
3. Step 3: Cross multiply
   1,380.24x = 1,904.43 × 1,007.31
4. Step 4: Simplify right side
   1,380.24x = 1,918,351.38
5. Step 5: Solve for x
   x = 1,918,351.38/1,380.24
6. Step 6: Final answer
   x = 1,389.87