Finding the Fourth Proportional to 1,080.42, 1,490.96 and 660.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,080.42 : 1,490.96 = 660.78 : x
2. Step 2: Convert to fraction form
   1,080.42/1,490.96 = 660.78/x
3. Step 3: Cross multiply
   1,080.42x = 1,490.96 × 660.78
4. Step 4: Simplify right side
   1,080.42x = 985,185.79
5. Step 5: Solve for x
   x = 985,185.79/1,080.42
6. Step 6: Final answer
   x = 911.85