Finding the Fourth Proportional to 2,116.25, 2,920.22 and 1,220.15

Step by Step Solution

1. Step 1: Write the proportion equation
   2,116.25 : 2,920.22 = 1,220.15 : x
2. Step 2: Convert to fraction form
   2,116.25/2,920.22 = 1,220.15/x
3. Step 3: Cross multiply
   2,116.25x = 2,920.22 × 1,220.15
4. Step 4: Simplify right side
   2,116.25x = 3,563,085.73
5. Step 5: Solve for x
   x = 3,563,085.73/2,116.25
6. Step 6: Final answer
   x = 1,683.68