Finding the Fourth Proportional to 2,196.80, 3,287.20 and 1,620.80

Step by Step Solution

1. Step 1: Write the proportion equation
   2,196.80 : 3,287.20 = 1,620.80 : x
2. Step 2: Convert to fraction form
   2,196.80/3,287.20 = 1,620.80/x
3. Step 3: Cross multiply
   2,196.80x = 3,287.20 × 1,620.80
4. Step 4: Simplify right side
   2,196.80x = 5,327,893.76
5. Step 5: Solve for x
   x = 5,327,893.76/2,196.80
6. Step 6: Final answer
   x = 2,425.30