Finding the Fourth Proportional to 2,215.98, 3,057.91 and 1,221.21

Step by Step Solution

1. Step 1: Write the proportion equation
   2,215.98 : 3,057.91 = 1,221.21 : x
2. Step 2: Convert to fraction form
   2,215.98/3,057.91 = 1,221.21/x
3. Step 3: Cross multiply
   2,215.98x = 3,057.91 × 1,221.21
4. Step 4: Simplify right side
   2,215.98x = 3,734,350.27
5. Step 5: Solve for x
   x = 3,734,350.27/2,215.98
6. Step 6: Final answer
   x = 1,685.19