Finding the Fourth Proportional to 20,821.33, 28,728.83 and 12,756.69

Step by Step Solution

1. Step 1: Write the proportion equation
   20,821.33 : 28,728.83 = 12,756.69 : x
2. Step 2: Convert to fraction form
   20,821.33/28,728.83 = 12,756.69/x
3. Step 3: Cross multiply
   20,821.33x = 28,728.83 × 12,756.69
4. Step 4: Simplify right side
   20,821.33x = 366,484,570.95
5. Step 5: Solve for x
   x = 366,484,570.95/20,821.33
6. Step 6: Final answer
   x = 17,601.40