Finding the Fourth Proportional to 21,204, 29,268.81 and 12,820.50

Step by Step Solution

1. Step 1: Write the proportion equation
   21,204 : 29,268.81 = 12,820.50 : x
2. Step 2: Convert to fraction form
   21,204/29,268.81 = 12,820.50/x
3. Step 3: Cross multiply
   21,204x = 29,268.81 × 12,820.50
4. Step 4: Simplify right side
   21,204x = 375,240,778.61
5. Step 5: Solve for x
   x = 375,240,778.61/21,204
6. Step 6: Final answer
   x = 17,696.70