Finding the Fourth Proportional to 3,933.89, 5,428.78 and 2,165.51

Step by Step Solution

1. Step 1: Write the proportion equation
   3,933.89 : 5,428.78 = 2,165.51 : x
2. Step 2: Convert to fraction form
   3,933.89/5,428.78 = 2,165.51/x
3. Step 3: Cross multiply
   3,933.89x = 5,428.78 × 2,165.51
4. Step 4: Simplify right side
   3,933.89x = 11,756,044.82
5. Step 5: Solve for x
   x = 11,756,044.82/3,933.89
6. Step 6: Final answer
   x = 2,988.40