Finding the Fourth Proportional to 3,699.68, 5,105.86 and 2,128.28

Step by Step Solution

1. Step 1: Write the proportion equation
   3,699.68 : 5,105.86 = 2,128.28 : x
2. Step 2: Convert to fraction form
   3,699.68/5,105.86 = 2,128.28/x
3. Step 3: Cross multiply
   3,699.68x = 5,105.86 × 2,128.28
4. Step 4: Simplify right side
   3,699.68x = 10,866,699.72
5. Step 5: Solve for x
   x = 10,866,699.72/3,699.68
6. Step 6: Final answer
   x = 2,937.20