Finding the Fourth Proportional to 3,896.95, 5,377.92 and 2,128.72

Step by Step Solution

1. Step 1: Write the proportion equation
   3,896.95 : 5,377.92 = 2,128.72 : x
2. Step 2: Convert to fraction form
   3,896.95/5,377.92 = 2,128.72/x
3. Step 3: Cross multiply
   3,896.95x = 5,377.92 × 2,128.72
4. Step 4: Simplify right side
   3,896.95x = 11,448,085.86
5. Step 5: Solve for x
   x = 11,448,085.86/3,896.95
6. Step 6: Final answer
   x = 2,937.70