Finding the Fourth Proportional to 1,398.30, 1,929.31 and 838.81

Step by Step Solution

1. Step 1: Write the proportion equation
   1,398.30 : 1,929.31 = 838.81 : x
2. Step 2: Convert to fraction form
   1,398.30/1,929.31 = 838.81/x
3. Step 3: Cross multiply
   1,398.30x = 1,929.31 × 838.81
4. Step 4: Simplify right side
   1,398.30x = 1,618,324.52
5. Step 5: Solve for x
   x = 1,618,324.52/1,398.30
6. Step 6: Final answer
   x = 1,157.35