Finding the Fourth Proportional to 1,399.05, 1,930.12 and 839.53

Step by Step Solution

1. Step 1: Write the proportion equation
   1,399.05 : 1,930.12 = 839.53 : x
2. Step 2: Convert to fraction form
   1,399.05/1,930.12 = 839.53/x
3. Step 3: Cross multiply
   1,399.05x = 1,930.12 × 839.53
4. Step 4: Simplify right side
   1,399.05x = 1,620,393.64
5. Step 5: Solve for x
   x = 1,620,393.64/1,399.05
6. Step 6: Final answer
   x = 1,158.21