Finding the Fourth Proportional to 1,380.84, 2,078.72 and 1,261.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.84 : 2,078.72 = 1,261.80 : x
2. Step 2: Convert to fraction form
   1,380.84/2,078.72 = 1,261.80/x
3. Step 3: Cross multiply
   1,380.84x = 2,078.72 × 1,261.80
4. Step 4: Simplify right side
   1,380.84x = 2,622,928.90
5. Step 5: Solve for x
   x = 2,622,928.90/1,380.84
6. Step 6: Final answer
   x = 1,899.52