Finding the Fourth Proportional to 2,105.98, 2,906.52 and 1,221.80

Step by Step Solution

1. Step 1: Write the proportion equation
   2,105.98 : 2,906.52 = 1,221.80 : x
2. Step 2: Convert to fraction form
   2,105.98/2,906.52 = 1,221.80/x
3. Step 3: Cross multiply
   2,105.98x = 2,906.52 × 1,221.80
4. Step 4: Simplify right side
   2,105.98x = 3,551,167.02
5. Step 5: Solve for x
   x = 3,551,167.02/2,105.98
6. Step 6: Final answer
   x = 1,686.23