Finding the Fourth Proportional to 2,166.96, 2,990.32 and 1,222.80

Step by Step Solution

1. Step 1: Write the proportion equation
   2,166.96 : 2,990.32 = 1,222.80 : x
2. Step 2: Convert to fraction form
   2,166.96/2,990.32 = 1,222.80/x
3. Step 3: Cross multiply
   2,166.96x = 2,990.32 × 1,222.80
4. Step 4: Simplify right side
   2,166.96x = 3,656,563.30
5. Step 5: Solve for x
   x = 3,656,563.30/2,166.96
6. Step 6: Final answer
   x = 1,687.42