Finding the Fourth Proportional to 1,421.40, 1,961.71 and 831.94

Step by Step Solution

1. Step 1: Write the proportion equation
   1,421.40 : 1,961.71 = 831.94 : x
2. Step 2: Convert to fraction form
   1,421.40/1,961.71 = 831.94/x
3. Step 3: Cross multiply
   1,421.40x = 1,961.71 × 831.94
4. Step 4: Simplify right side
   1,421.40x = 1,632,016.86
5. Step 5: Solve for x
   x = 1,632,016.86/1,421.40
6. Step 6: Final answer
   x = 1,148.17