Finding the Fourth Proportional to 11,561.76, 17,337.78 and 8,422.20

Step by Step Solution

1. Step 1: Write the proportion equation
   11,561.76 : 17,337.78 = 8,422.20 : x
2. Step 2: Convert to fraction form
   11,561.76/17,337.78 = 8,422.20/x
3. Step 3: Cross multiply
   11,561.76x = 17,337.78 × 8,422.20
4. Step 4: Simplify right side
   11,561.76x = 146,022,250.72
5. Step 5: Solve for x
   x = 146,022,250.72/11,561.76
6. Step 6: Final answer
   x = 12,629.76