Finding the Fourth Proportional to 1,080.42, 1,491.69 and 831.30

Step by Step Solution

1. Step 1: Write the proportion equation
   1,080.42 : 1,491.69 = 831.30 : x
2. Step 2: Convert to fraction form
   1,080.42/1,491.69 = 831.30/x
3. Step 3: Cross multiply
   1,080.42x = 1,491.69 × 831.30
4. Step 4: Simplify right side
   1,080.42x = 1,240,041.90
5. Step 5: Solve for x
   x = 1,240,041.90/1,080.42
6. Step 6: Final answer
   x = 1,147.74