Finding the Fourth Proportional to 12,960.78, 17,888.55 and 8,429.14

Step by Step Solution

1. Step 1: Write the proportion equation
   12,960.78 : 17,888.55 = 8,429.14 : x
2. Step 2: Convert to fraction form
   12,960.78/17,888.55 = 8,429.14/x
3. Step 3: Cross multiply
   12,960.78x = 17,888.55 × 8,429.14
4. Step 4: Simplify right side
   12,960.78x = 150,785,092.35
5. Step 5: Solve for x
   x = 150,785,092.35/12,960.78
6. Step 6: Final answer
   x = 11,633.95