Finding the Fourth Proportional to 20,738.16, 28,623.08 and 13,665.20

Step by Step Solution

1. Step 1: Write the proportion equation
   20,738.16 : 28,623.08 = 13,665.20 : x
2. Step 2: Convert to fraction form
   20,738.16/28,623.08 = 13,665.20/x
3. Step 3: Cross multiply
   20,738.16x = 28,623.08 × 13,665.20
4. Step 4: Simplify right side
   20,738.16x = 391,140,112.82
5. Step 5: Solve for x
   x = 391,140,112.82/20,738.16
6. Step 6: Final answer
   x = 18,860.89