Finding the Fourth Proportional to 21,121.20, 31,680.18 and 5,538.42

Step by Step Solution

1. Step 1: Write the proportion equation
   21,121.20 : 31,680.18 = 5,538.42 : x
2. Step 2: Convert to fraction form
   21,121.20/31,680.18 = 5,538.42/x
3. Step 3: Cross multiply
   21,121.20x = 31,680.18 × 5,538.42
4. Step 4: Simplify right side
   21,121.20x = 175,458,142.52
5. Step 5: Solve for x
   x = 175,458,142.52/21,121.20
6. Step 6: Final answer
   x = 8,307.21