Finding the Fourth Proportional to 13,478.72, 18,618.78 and 12,221.18

Step by Step Solution

1. Step 1: Write the proportion equation
   13,478.72 : 18,618.78 = 12,221.18 : x
2. Step 2: Convert to fraction form
   13,478.72/18,618.78 = 12,221.18/x
3. Step 3: Cross multiply
   13,478.72x = 18,618.78 × 12,221.18
4. Step 4: Simplify right side
   13,478.72x = 227,543,461.76
5. Step 5: Solve for x
   x = 227,543,461.76/13,478.72
6. Step 6: Final answer
   x = 16,881.68