Finding the Fourth Proportional to 1,399.56, 1,931.19 and 839.91

Step by Step Solution

1. Step 1: Write the proportion equation
   1,399.56 : 1,931.19 = 839.91 : x
2. Step 2: Convert to fraction form
   1,399.56/1,931.19 = 839.91/x
3. Step 3: Cross multiply
   1,399.56x = 1,931.19 × 839.91
4. Step 4: Simplify right side
   1,399.56x = 1,622,025.79
5. Step 5: Solve for x
   x = 1,622,025.79/1,399.56
6. Step 6: Final answer
   x = 1,158.95