Finding the Fourth Proportional to 2,388.40, 3,296.88 and 2,139.28

Step by Step Solution

1. Step 1: Write the proportion equation
   2,388.40 : 3,296.88 = 2,139.28 : x
2. Step 2: Convert to fraction form
   2,388.40/3,296.88 = 2,139.28/x
3. Step 3: Cross multiply
   2,388.40x = 3,296.88 × 2,139.28
4. Step 4: Simplify right side
   2,388.40x = 7,052,949.45
5. Step 5: Solve for x
   x = 7,052,949.45/2,388.40
6. Step 6: Final answer
   x = 2,953.00