Finding the Fourth Proportional to 1,420.69, 1,960.56 and 831.34

Step by Step Solution

1. Step 1: Write the proportion equation
   1,420.69 : 1,960.56 = 831.34 : x
2. Step 2: Convert to fraction form
   1,420.69/1,960.56 = 831.34/x
3. Step 3: Cross multiply
   1,420.69x = 1,960.56 × 831.34
4. Step 4: Simplify right side
   1,420.69x = 1,629,887.79
5. Step 5: Solve for x
   x = 1,629,887.79/1,420.69
6. Step 6: Final answer
   x = 1,147.25