Finding the Fourth Proportional to 12,429.56, 18,636.91 and 8,431.86

Step by Step Solution

1. Step 1: Write the proportion equation
   12,429.56 : 18,636.91 = 8,431.86 : x
2. Step 2: Convert to fraction form
   12,429.56/18,636.91 = 8,431.86/x
3. Step 3: Cross multiply
   12,429.56x = 18,636.91 × 8,431.86
4. Step 4: Simplify right side
   12,429.56x = 157,143,786.14
5. Step 5: Solve for x
   x = 157,143,786.14/12,429.56
6. Step 6: Final answer
   x = 12,642.74