Finding the Fourth Proportional to 21,665.50, 29,900.60 and 15,620.72

Step by Step Solution

1. Step 1: Write the proportion equation
   21,665.50 : 29,900.60 = 15,620.72 : x
2. Step 2: Convert to fraction form
   21,665.50/29,900.60 = 15,620.72/x
3. Step 3: Cross multiply
   21,665.50x = 29,900.60 × 15,620.72
4. Step 4: Simplify right side
   21,665.50x = 467,068,731.40
5. Step 5: Solve for x
   x = 467,068,731.40/21,665.50
6. Step 6: Final answer
   x = 21,558.18