Finding the Fourth Proportional to 1,421.30, 1,961.73 and 831.89

Step by Step Solution

1. Step 1: Write the proportion equation
   1,421.30 : 1,961.73 = 831.89 : x
2. Step 2: Convert to fraction form
   1,421.30/1,961.73 = 831.89/x
3. Step 3: Cross multiply
   1,421.30x = 1,961.73 × 831.89
4. Step 4: Simplify right side
   1,421.30x = 1,631,933.76
5. Step 5: Solve for x
   x = 1,631,933.76/1,421.30
6. Step 6: Final answer
   x = 1,148.20