Finding the Fourth Proportional to 1,398.10, 1,928.76 and 838.30

Step by Step Solution

1. Step 1: Write the proportion equation
   1,398.10 : 1,928.76 = 838.30 : x
2. Step 2: Convert to fraction form
   1,398.10/1,928.76 = 838.30/x
3. Step 3: Cross multiply
   1,398.10x = 1,928.76 × 838.30
4. Step 4: Simplify right side
   1,398.10x = 1,616,879.51
5. Step 5: Solve for x
   x = 1,616,879.51/1,398.10
6. Step 6: Final answer
   x = 1,156.48