Finding the Fourth Proportional to 1,380.59, 1,905.49 and 783.09

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.59 : 1,905.49 = 783.09 : x
2. Step 2: Convert to fraction form
   1,380.59/1,905.49 = 783.09/x
3. Step 3: Cross multiply
   1,380.59x = 1,905.49 × 783.09
4. Step 4: Simplify right side
   1,380.59x = 1,492,171.01
5. Step 5: Solve for x
   x = 1,492,171.01/1,380.59
6. Step 6: Final answer
   x = 1,080.82