Finding the Fourth Proportional to 1,398.78, 1,930.16 and 839.14

Step by Step Solution

1. Step 1: Write the proportion equation
   1,398.78 : 1,930.16 = 839.14 : x
2. Step 2: Convert to fraction form
   1,398.78/1,930.16 = 839.14/x
3. Step 3: Cross multiply
   1,398.78x = 1,930.16 × 839.14
4. Step 4: Simplify right side
   1,398.78x = 1,619,674.46
5. Step 5: Solve for x
   x = 1,619,674.46/1,398.78
6. Step 6: Final answer
   x = 1,157.92