Finding the Fourth Proportional to 11,868.50, 16,369.62 and 9,990.12

Step by Step Solution

1. Step 1: Write the proportion equation
   11,868.50 : 16,369.62 = 9,990.12 : x
2. Step 2: Convert to fraction form
   11,868.50/16,369.62 = 9,990.12/x
3. Step 3: Cross multiply
   11,868.50x = 16,369.62 × 9,990.12
4. Step 4: Simplify right side
   11,868.50x = 163,534,468.15
5. Step 5: Solve for x
   x = 163,534,468.15/11,868.50
6. Step 6: Final answer
   x = 13,778.87