Finding the Fourth Proportional to 1,390.56, 1,919.79 and 867.30

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.56 : 1,919.79 = 867.30 : x
2. Step 2: Convert to fraction form
   1,390.56/1,919.79 = 867.30/x
3. Step 3: Cross multiply
   1,390.56x = 1,919.79 × 867.30
4. Step 4: Simplify right side
   1,390.56x = 1,665,033.87
5. Step 5: Solve for x
   x = 1,665,033.87/1,390.56
6. Step 6: Final answer
   x = 1,197.38