Finding the Fourth Proportional to 1,390.69, 1,919.60 and 919.00

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.69 : 1,919.60 = 919.00 : x
2. Step 2: Convert to fraction form
   1,390.69/1,919.60 = 919.00/x
3. Step 3: Cross multiply
   1,390.69x = 1,919.60 × 919.00
4. Step 4: Simplify right side
   1,390.69x = 1,764,119.05
5. Step 5: Solve for x
   x = 1,764,119.05/1,390.69
6. Step 6: Final answer
   x = 1,268.52