Finding the Fourth Proportional to 2,778.05, 4,165.12 and 1,390.40

Step by Step Solution

1. Step 1: Write the proportion equation
   2,778.05 : 4,165.12 = 1,390.40 : x
2. Step 2: Convert to fraction form
   2,778.05/4,165.12 = 1,390.40/x
3. Step 3: Cross multiply
   2,778.05x = 4,165.12 × 1,390.40
4. Step 4: Simplify right side
   2,778.05x = 5,791,158.55
5. Step 5: Solve for x
   x = 5,791,158.55/2,778.05
6. Step 6: Final answer
   x = 2,084.61