Finding the Fourth Proportional to 1,391.30, 1,918.86 and 998.54

Step by Step Solution

1. Step 1: Write the proportion equation
   1,391.30 : 1,918.86 = 998.54 : x
2. Step 2: Convert to fraction form
   1,391.30/1,918.86 = 998.54/x
3. Step 3: Cross multiply
   1,391.30x = 1,918.86 × 998.54
4. Step 4: Simplify right side
   1,391.30x = 1,916,058.46
5. Step 5: Solve for x
   x = 1,916,058.46/1,391.30
6. Step 6: Final answer
   x = 1,377.17