Finding the Fourth Proportional to 3,897.72, 5,378.79 and 2,129.31

Step by Step Solution

1. Step 1: Write the proportion equation
   3,897.72 : 5,378.79 = 2,129.31 : x
2. Step 2: Convert to fraction form
   3,897.72/5,378.79 = 2,129.31/x
3. Step 3: Cross multiply
   3,897.72x = 5,378.79 × 2,129.31
4. Step 4: Simplify right side
   3,897.72x = 11,453,111.33
5. Step 5: Solve for x
   x = 11,453,111.33/3,897.72
6. Step 6: Final answer
   x = 2,938.41