Finding the Fourth Proportional to 12,538.72, 18,807.90 and 4,220.56

Step by Step Solution

1. Step 1: Write the proportion equation
   12,538.72 : 18,807.90 = 4,220.56 : x
2. Step 2: Convert to fraction form
   12,538.72/18,807.90 = 4,220.56/x
3. Step 3: Cross multiply
   12,538.72x = 18,807.90 × 4,220.56
4. Step 4: Simplify right side
   12,538.72x = 79,379,870.42
5. Step 5: Solve for x
   x = 79,379,870.42/12,538.72
6. Step 6: Final answer
   x = 6,330.78