Finding the Fourth Proportional to 3,543.72, 4,890.78 and 2,128.20

Step by Step Solution

1. Step 1: Write the proportion equation
   3,543.72 : 4,890.78 = 2,128.20 : x
2. Step 2: Convert to fraction form
   3,543.72/4,890.78 = 2,128.20/x
3. Step 3: Cross multiply
   3,543.72x = 4,890.78 × 2,128.20
4. Step 4: Simplify right side
   3,543.72x = 10,408,558.00
5. Step 5: Solve for x
   x = 10,408,558.00/3,543.72
6. Step 6: Final answer
   x = 2,937.18