Finding the Fourth Proportional to 2,105.85, 2,905.63 and 1,221.54

Step by Step Solution

1. Step 1: Write the proportion equation
   2,105.85 : 2,905.63 = 1,221.54 : x
2. Step 2: Convert to fraction form
   2,105.85/2,905.63 = 1,221.54/x
3. Step 3: Cross multiply
   2,105.85x = 2,905.63 × 1,221.54
4. Step 4: Simplify right side
   2,105.85x = 3,549,340.22
5. Step 5: Solve for x
   x = 3,549,340.22/2,105.85
6. Step 6: Final answer
   x = 1,685.47