Finding the Fourth Proportional to 998.20, 1,504.78 and 931.31

Step by Step Solution

1. Step 1: Write the proportion equation
   998.20 : 1,504.78 = 931.31 : x
2. Step 2: Convert to fraction form
   998.20/1,504.78 = 931.31/x
3. Step 3: Cross multiply
   998.20x = 1,504.78 × 931.31
4. Step 4: Simplify right side
   998.20x = 1,401,404.48
5. Step 5: Solve for x
   x = 1,401,404.48/998.20
6. Step 6: Final answer
   x = 1,403.94