Finding the Fourth Proportional to 21,131.66, 29,161.72 and 13,578.02

Step by Step Solution

1. Step 1: Write the proportion equation
   21,131.66 : 29,161.72 = 13,578.02 : x
2. Step 2: Convert to fraction form
   21,131.66/29,161.72 = 13,578.02/x
3. Step 3: Cross multiply
   21,131.66x = 29,161.72 × 13,578.02
4. Step 4: Simplify right side
   21,131.66x = 395,958,417.39
5. Step 5: Solve for x
   x = 395,958,417.39/21,131.66
6. Step 6: Final answer
   x = 18,737.69