Finding the Fourth Proportional to 1,396.78, 1,940.91 and 1,381.59

Step by Step Solution

1. Step 1: Write the proportion equation
   1,396.78 : 1,940.91 = 1,381.59 : x
2. Step 2: Convert to fraction form
   1,396.78/1,940.91 = 1,381.59/x
3. Step 3: Cross multiply
   1,396.78x = 1,940.91 × 1,381.59
4. Step 4: Simplify right side
   1,396.78x = 2,681,532.14
5. Step 5: Solve for x
   x = 2,681,532.14/1,396.78
6. Step 6: Final answer
   x = 1,919.80