Finding the Fourth Proportional to 21,216.53, 29,298.51 and 13,680.50

Step by Step Solution

1. Step 1: Write the proportion equation
   21,216.53 : 29,298.51 = 13,680.50 : x
2. Step 2: Convert to fraction form
   21,216.53/29,298.51 = 13,680.50/x
3. Step 3: Cross multiply
   21,216.53x = 29,298.51 × 13,680.50
4. Step 4: Simplify right side
   21,216.53x = 400,818,119.56
5. Step 5: Solve for x
   x = 400,818,119.56/21,216.53
6. Step 6: Final answer
   x = 18,891.78