Finding the Fourth Proportional to 12,338.78, 18,390.86 and 11,638.18

Step by Step Solution

1. Step 1: Write the proportion equation
   12,338.78 : 18,390.86 = 11,638.18 : x
2. Step 2: Convert to fraction form
   12,338.78/18,390.86 = 11,638.18/x
3. Step 3: Cross multiply
   12,338.78x = 18,390.86 × 11,638.18
4. Step 4: Simplify right side
   12,338.78x = 214,036,139.03
5. Step 5: Solve for x
   x = 214,036,139.03/12,338.78
6. Step 6: Final answer
   x = 17,346.62