Finding the Fourth Proportional to 1,111.31, 1,531.89 and 831.12

Step by Step Solution

1. Step 1: Write the proportion equation
   1,111.31 : 1,531.89 = 831.12 : x
2. Step 2: Convert to fraction form
   1,111.31/1,531.89 = 831.12/x
3. Step 3: Cross multiply
   1,111.31x = 1,531.89 × 831.12
4. Step 4: Simplify right side
   1,111.31x = 1,273,178.67
5. Step 5: Solve for x
   x = 1,273,178.67/1,111.31
6. Step 6: Final answer
   x = 1,145.66