Finding the Fourth Proportional to 2,187.78, 3,019.63 and 1,390.95

Step by Step Solution

1. Step 1: Write the proportion equation
   2,187.78 : 3,019.63 = 1,390.95 : x
2. Step 2: Convert to fraction form
   2,187.78/3,019.63 = 1,390.95/x
3. Step 3: Cross multiply
   2,187.78x = 3,019.63 × 1,390.95
4. Step 4: Simplify right side
   2,187.78x = 4,200,150.87
5. Step 5: Solve for x
   x = 4,200,150.87/2,187.78
6. Step 6: Final answer
   x = 1,919.82