Finding the Fourth Proportional to 2,978.72, 4,108.20 and 2,139.56

Step by Step Solution

1. Step 1: Write the proportion equation
   2,978.72 : 4,108.20 = 2,139.56 : x
2. Step 2: Convert to fraction form
   2,978.72/4,108.20 = 2,139.56/x
3. Step 3: Cross multiply
   2,978.72x = 4,108.20 × 2,139.56
4. Step 4: Simplify right side
   2,978.72x = 8,789,740.39
5. Step 5: Solve for x
   x = 8,789,740.39/2,978.72
6. Step 6: Final answer
   x = 2,950.84