Finding the Fourth Proportional to 21,028.50, 31,478.34 and 13,618.22

Step by Step Solution

1. Step 1: Write the proportion equation
   21,028.50 : 31,478.34 = 13,618.22 : x
2. Step 2: Convert to fraction form
   21,028.50/31,478.34 = 13,618.22/x
3. Step 3: Cross multiply
   21,028.50x = 31,478.34 × 13,618.22
4. Step 4: Simplify right side
   21,028.50x = 428,678,959.35
5. Step 5: Solve for x
   x = 428,678,959.35/21,028.50
6. Step 6: Final answer
   x = 20,385.62