Finding the Fourth Proportional to 21,021.12, 31,510.42 and 13,630.28

Step by Step Solution

1. Step 1: Write the proportion equation
   21,021.12 : 31,510.42 = 13,630.28 : x
2. Step 2: Convert to fraction form
   21,021.12/31,510.42 = 13,630.28/x
3. Step 3: Cross multiply
   21,021.12x = 31,510.42 × 13,630.28
4. Step 4: Simplify right side
   21,021.12x = 429,495,655.89
5. Step 5: Solve for x
   x = 429,495,655.89/21,021.12
6. Step 6: Final answer
   x = 20,431.63