Finding the Fourth Proportional to 1,398.50, 1,928.39 and 1,099.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,398.50 : 1,928.39 = 1,099.78 : x
2. Step 2: Convert to fraction form
   1,398.50/1,928.39 = 1,099.78/x
3. Step 3: Cross multiply
   1,398.50x = 1,928.39 × 1,099.78
4. Step 4: Simplify right side
   1,398.50x = 2,120,794.43
5. Step 5: Solve for x
   x = 2,120,794.43/1,398.50
6. Step 6: Final answer
   x = 1,516.48