Finding the Fourth Proportional to 21,315.88, 29,424.72 and 13,356.28

Step by Step Solution

1. Step 1: Write the proportion equation
   21,315.88 : 29,424.72 = 13,356.28 : x
2. Step 2: Convert to fraction form
   21,315.88/29,424.72 = 13,356.28/x
3. Step 3: Cross multiply
   21,315.88x = 29,424.72 × 13,356.28
4. Step 4: Simplify right side
   21,315.88x = 393,004,799.24
5. Step 5: Solve for x
   x = 393,004,799.24/21,315.88
6. Step 6: Final answer
   x = 18,437.18