Finding the Fourth Proportional to 2,105.24, 2,905.12 and 1,221

Step by Step Solution

1. Step 1: Write the proportion equation
   2,105.24 : 2,905.12 = 1,221 : x
2. Step 2: Convert to fraction form
   2,105.24/2,905.12 = 1,221/x
3. Step 3: Cross multiply
   2,105.24x = 2,905.12 × 1,221
4. Step 4: Simplify right side
   2,105.24x = 3,547,151.52
5. Step 5: Solve for x
   x = 3,547,151.52/2,105.24
6. Step 6: Final answer
   x = 1,684.92