Finding the Fourth Proportional to 2,651.72, 3,978.39 and 921.56

Step by Step Solution

1. Step 1: Write the proportion equation
   2,651.72 : 3,978.39 = 921.56 : x
2. Step 2: Convert to fraction form
   2,651.72/3,978.39 = 921.56/x
3. Step 3: Cross multiply
   2,651.72x = 3,978.39 × 921.56
4. Step 4: Simplify right side
   2,651.72x = 3,666,325.09
5. Step 5: Solve for x
   x = 3,666,325.09/2,651.72
6. Step 6: Final answer
   x = 1,382.62