Finding the Fourth Proportional to 3,915.42, 5,399.61 and 3,121.38

Step by Step Solution

1. Step 1: Write the proportion equation
   3,915.42 : 5,399.61 = 3,121.38 : x
2. Step 2: Convert to fraction form
   3,915.42/5,399.61 = 3,121.38/x
3. Step 3: Cross multiply
   3,915.42x = 5,399.61 × 3,121.38
4. Step 4: Simplify right side
   3,915.42x = 16,854,221.16
5. Step 5: Solve for x
   x = 16,854,221.16/3,915.42
6. Step 6: Final answer
   x = 4,304.58