Finding the Fourth Proportional to 1,391.31, 1,918.62 and 919.62

Step by Step Solution

1. Step 1: Write the proportion equation
   1,391.31 : 1,918.62 = 919.62 : x
2. Step 2: Convert to fraction form
   1,391.31/1,918.62 = 919.62/x
3. Step 3: Cross multiply
   1,391.31x = 1,918.62 × 919.62
4. Step 4: Simplify right side
   1,391.31x = 1,764,401.32
5. Step 5: Solve for x
   x = 1,764,401.32/1,391.31
6. Step 6: Final answer
   x = 1,268.16