Finding the Fourth Proportional to 2,105.51, 2,905.61 and 1,221.48

Step by Step Solution

1. Step 1: Write the proportion equation
   2,105.51 : 2,905.61 = 1,221.48 : x
2. Step 2: Convert to fraction form
   2,105.51/2,905.61 = 1,221.48/x
3. Step 3: Cross multiply
   2,105.51x = 2,905.61 × 1,221.48
4. Step 4: Simplify right side
   2,105.51x = 3,549,138.40
5. Step 5: Solve for x
   x = 3,549,138.40/2,105.51
6. Step 6: Final answer
   x = 1,685.65