Finding the Fourth Proportional to 5,215.20, 7,196.88 and 2,857.28

Step by Step Solution

1. Step 1: Write the proportion equation
   5,215.20 : 7,196.88 = 2,857.28 : x
2. Step 2: Convert to fraction form
   5,215.20/7,196.88 = 2,857.28/x
3. Step 3: Cross multiply
   5,215.20x = 7,196.88 × 2,857.28
4. Step 4: Simplify right side
   5,215.20x = 20,563,501.29
5. Step 5: Solve for x
   x = 20,563,501.29/5,215.20
6. Step 6: Final answer
   x = 3,942.99