Finding the Fourth Proportional to 1,080.20, 1,490.72 and 660.45

Step by Step Solution

1. Step 1: Write the proportion equation
   1,080.20 : 1,490.72 = 660.45 : x
2. Step 2: Convert to fraction form
   1,080.20/1,490.72 = 660.45/x
3. Step 3: Cross multiply
   1,080.20x = 1,490.72 × 660.45
4. Step 4: Simplify right side
   1,080.20x = 984,542.72
5. Step 5: Solve for x
   x = 984,542.72/1,080.20
6. Step 6: Final answer
   x = 911.45