Finding the Fourth Proportional to 21,279.69, 29,361.87 and 13,724.55

Step by Step Solution

1. Step 1: Write the proportion equation
   21,279.69 : 29,361.87 = 13,724.55 : x
2. Step 2: Convert to fraction form
   21,279.69/29,361.87 = 13,724.55/x
3. Step 3: Cross multiply
   21,279.69x = 29,361.87 × 13,724.55
4. Step 4: Simplify right side
   21,279.69x = 402,978,452.91
5. Step 5: Solve for x
   x = 402,978,452.91/21,279.69
6. Step 6: Final answer
   x = 18,937.23