Finding the Fourth Proportional to 1,380.88, 2,069.55 and 919.56

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.88 : 2,069.55 = 919.56 : x
2. Step 2: Convert to fraction form
   1,380.88/2,069.55 = 919.56/x
3. Step 3: Cross multiply
   1,380.88x = 2,069.55 × 919.56
4. Step 4: Simplify right side
   1,380.88x = 1,903,071.52
5. Step 5: Solve for x
   x = 1,903,071.52/1,380.88
6. Step 6: Final answer
   x = 1,378.16