Finding the Fourth Proportional to 2,105.40, 2,905.38 and 1,221.06

Step by Step Solution

1. Step 1: Write the proportion equation
   2,105.40 : 2,905.38 = 1,221.06 : x
2. Step 2: Convert to fraction form
   2,105.40/2,905.38 = 1,221.06/x
3. Step 3: Cross multiply
   2,105.40x = 2,905.38 × 1,221.06
4. Step 4: Simplify right side
   2,105.40x = 3,547,643.30
5. Step 5: Solve for x
   x = 3,547,643.30/2,105.40
6. Step 6: Final answer
   x = 1,685.02