Finding the Fourth Proportional to 8,667.60, 12,993.42 and 2,821.20

Step by Step Solution

1. Step 1: Write the proportion equation
   8,667.60 : 12,993.42 = 2,821.20 : x
2. Step 2: Convert to fraction form
   8,667.60/12,993.42 = 2,821.20/x
3. Step 3: Cross multiply
   8,667.60x = 12,993.42 × 2,821.20
4. Step 4: Simplify right side
   8,667.60x = 36,657,036.50
5. Step 5: Solve for x
   x = 36,657,036.50/8,667.60
6. Step 6: Final answer
   x = 4,229.20