Finding the Fourth Proportional to 2,143.72, 3,215.78 and 756.90

Step by Step Solution

1. Step 1: Write the proportion equation
   2,143.72 : 3,215.78 = 756.90 : x
2. Step 2: Convert to fraction form
   2,143.72/3,215.78 = 756.90/x
3. Step 3: Cross multiply
   2,143.72x = 3,215.78 × 756.90
4. Step 4: Simplify right side
   2,143.72x = 2,434,023.88
5. Step 5: Solve for x
   x = 2,434,023.88/2,143.72
6. Step 6: Final answer
   x = 1,135.42