Finding the Fourth Proportional to 1,399.10, 1,930.87 and 839.59

Step by Step Solution

1. Step 1: Write the proportion equation
   1,399.10 : 1,930.87 = 839.59 : x
2. Step 2: Convert to fraction form
   1,399.10/1,930.87 = 839.59/x
3. Step 3: Cross multiply
   1,399.10x = 1,930.87 × 839.59
4. Step 4: Simplify right side
   1,399.10x = 1,621,139.14
5. Step 5: Solve for x
   x = 1,621,139.14/1,399.10
6. Step 6: Final answer
   x = 1,158.70