Finding the Fourth Proportional to 12,171.78, 18,209.64 and 9,218.76

Step by Step Solution

1. Step 1: Write the proportion equation
   12,171.78 : 18,209.64 = 9,218.76 : x
2. Step 2: Convert to fraction form
   12,171.78/18,209.64 = 9,218.76/x
3. Step 3: Cross multiply
   12,171.78x = 18,209.64 × 9,218.76
4. Step 4: Simplify right side
   12,171.78x = 167,870,300.85
5. Step 5: Solve for x
   x = 167,870,300.85/12,171.78
6. Step 6: Final answer
   x = 13,791.76