Finding the Fourth Proportional to 3,940.65, 5,421.33 and 3,831.30

Step by Step Solution

1. Step 1: Write the proportion equation
   3,940.65 : 5,421.33 = 3,831.30 : x
2. Step 2: Convert to fraction form
   3,940.65/5,421.33 = 3,831.30/x
3. Step 3: Cross multiply
   3,940.65x = 5,421.33 × 3,831.30
4. Step 4: Simplify right side
   3,940.65x = 20,770,741.63
5. Step 5: Solve for x
   x = 20,770,741.63/3,940.65
6. Step 6: Final answer
   x = 5,270.89