Finding the Fourth Proportional to 3,945.90, 5,428.58 and 3,836.55

Step by Step Solution

1. Step 1: Write the proportion equation
   3,945.90 : 5,428.58 = 3,836.55 : x
2. Step 2: Convert to fraction form
   3,945.90/5,428.58 = 3,836.55/x
3. Step 3: Cross multiply
   3,945.90x = 5,428.58 × 3,836.55
4. Step 4: Simplify right side
   3,945.90x = 20,826,999.42
5. Step 5: Solve for x
   x = 20,826,999.42/3,945.90
6. Step 6: Final answer
   x = 5,278.14