Finding the Fourth Proportional to 2,216.40, 3,058.50 and 1,221.72

Step by Step Solution

1. Step 1: Write the proportion equation
   2,216.40 : 3,058.50 = 1,221.72 : x
2. Step 2: Convert to fraction form
   2,216.40/3,058.50 = 1,221.72/x
3. Step 3: Cross multiply
   2,216.40x = 3,058.50 × 1,221.72
4. Step 4: Simplify right side
   2,216.40x = 3,736,630.62
5. Step 5: Solve for x
   x = 3,736,630.62/2,216.40
6. Step 6: Final answer
   x = 1,685.90