Finding the Fourth Proportional to 2,138.72, 2,949.75 and 1,392.91

Step by Step Solution

1. Step 1: Write the proportion equation
   2,138.72 : 2,949.75 = 1,392.91 : x
2. Step 2: Convert to fraction form
   2,138.72/2,949.75 = 1,392.91/x
3. Step 3: Cross multiply
   2,138.72x = 2,949.75 × 1,392.91
4. Step 4: Simplify right side
   2,138.72x = 4,108,728.90
5. Step 5: Solve for x
   x = 4,108,728.90/2,138.72
6. Step 6: Final answer
   x = 1,921.12