Finding the Fourth Proportional to 1,380.31, 1,904.81 and 782.91

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.31 : 1,904.81 = 782.91 : x
2. Step 2: Convert to fraction form
   1,380.31/1,904.81 = 782.91/x
3. Step 3: Cross multiply
   1,380.31x = 1,904.81 × 782.91
4. Step 4: Simplify right side
   1,380.31x = 1,491,294.80
5. Step 5: Solve for x
   x = 1,491,294.80/1,380.31
6. Step 6: Final answer
   x = 1,080.41