Finding the Fourth Proportional to 1,080.55, 1,491.32 and 661.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,080.55 : 1,491.32 = 661.15 : x
2. Step 2: Convert to fraction form
   1,080.55/1,491.32 = 661.15/x
3. Step 3: Cross multiply
   1,080.55x = 1,491.32 × 661.15
4. Step 4: Simplify right side
   1,080.55x = 985,986.22
5. Step 5: Solve for x
   x = 985,986.22/1,080.55
6. Step 6: Final answer
   x = 912.49