Finding the Fourth Proportional to 21,730.96, 29,978.58 and 12,778.30

Step by Step Solution

1. Step 1: Write the proportion equation
   21,730.96 : 29,978.58 = 12,778.30 : x
2. Step 2: Convert to fraction form
   21,730.96/29,978.58 = 12,778.30/x
3. Step 3: Cross multiply
   21,730.96x = 29,978.58 × 12,778.30
4. Step 4: Simplify right side
   21,730.96x = 383,075,288.81
5. Step 5: Solve for x
   x = 383,075,288.81/21,730.96
6. Step 6: Final answer
   x = 17,628.09