Finding the Fourth Proportional to 2,168.30, 2,991.60 and 1,223.98

Step by Step Solution

1. Step 1: Write the proportion equation
   2,168.30 : 2,991.60 = 1,223.98 : x
2. Step 2: Convert to fraction form
   2,168.30/2,991.60 = 1,223.98/x
3. Step 3: Cross multiply
   2,168.30x = 2,991.60 × 1,223.98
4. Step 4: Simplify right side
   2,168.30x = 3,661,651.09
5. Step 5: Solve for x
   x = 3,661,651.09/2,168.30
6. Step 6: Final answer
   x = 1,688.72