Finding the Fourth Proportional to 21,638.72, 29,861.52 and 12,209.12

Step by Step Solution

1. Step 1: Write the proportion equation
   21,638.72 : 29,861.52 = 12,209.12 : x
2. Step 2: Convert to fraction form
   21,638.72/29,861.52 = 12,209.12/x
3. Step 3: Cross multiply
   21,638.72x = 29,861.52 × 12,209.12
4. Step 4: Simplify right side
   21,638.72x = 364,582,881.06
5. Step 5: Solve for x
   x = 364,582,881.06/21,638.72
6. Step 6: Final answer
   x = 16,848.63