Finding the Fourth Proportional to 1,080.50, 1,490.72 and 660.70

Step by Step Solution

1. Step 1: Write the proportion equation
   1,080.50 : 1,490.72 = 660.70 : x
2. Step 2: Convert to fraction form
   1,080.50/1,490.72 = 660.70/x
3. Step 3: Cross multiply
   1,080.50x = 1,490.72 × 660.70
4. Step 4: Simplify right side
   1,080.50x = 984,918.70
5. Step 5: Solve for x
   x = 984,918.70/1,080.50
6. Step 6: Final answer
   x = 911.54