Finding the Fourth Proportional to 1,421.27, 1,961.36 and 831.69

Step by Step Solution

1. Step 1: Write the proportion equation
   1,421.27 : 1,961.36 = 831.69 : x
2. Step 2: Convert to fraction form
   1,421.27/1,961.36 = 831.69/x
3. Step 3: Cross multiply
   1,421.27x = 1,961.36 × 831.69
4. Step 4: Simplify right side
   1,421.27x = 1,631,243.50
5. Step 5: Solve for x
   x = 1,631,243.50/1,421.27
6. Step 6: Final answer
   x = 1,147.74