Finding the Fourth Proportional to 1,098.72, 1,646.51 and 660.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,098.72 : 1,646.51 = 660.15 : x
2. Step 2: Convert to fraction form
   1,098.72/1,646.51 = 660.15/x
3. Step 3: Cross multiply
   1,098.72x = 1,646.51 × 660.15
4. Step 4: Simplify right side
   1,098.72x = 1,086,940.28
5. Step 5: Solve for x
   x = 1,086,940.28/1,098.72
6. Step 6: Final answer
   x = 989.28