Finding the Fourth Proportional to 21,722.91, 29,978.28 and 12,768.77

Step by Step Solution

1. Step 1: Write the proportion equation
   21,722.91 : 29,978.28 = 12,768.77 : x
2. Step 2: Convert to fraction form
   21,722.91/29,978.28 = 12,768.77/x
3. Step 3: Cross multiply
   21,722.91x = 29,978.28 × 12,768.77
4. Step 4: Simplify right side
   21,722.91x = 382,785,612.42
5. Step 5: Solve for x
   x = 382,785,612.42/21,722.91
6. Step 6: Final answer
   x = 17,621.29