Finding the Fourth Proportional to 1,380.97, 1,905.78 and 783.45

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.97 : 1,905.78 = 783.45 : x
2. Step 2: Convert to fraction form
   1,380.97/1,905.78 = 783.45/x
3. Step 3: Cross multiply
   1,380.97x = 1,905.78 × 783.45
4. Step 4: Simplify right side
   1,380.97x = 1,493,083.34
5. Step 5: Solve for x
   x = 1,493,083.34/1,380.97
6. Step 6: Final answer
   x = 1,081.18