Finding the Fourth Proportional to 3,111.28, 4,667.31 and 920.05

Step by Step Solution

1. Step 1: Write the proportion equation
   3,111.28 : 4,667.31 = 920.05 : x
2. Step 2: Convert to fraction form
   3,111.28/4,667.31 = 920.05/x
3. Step 3: Cross multiply
   3,111.28x = 4,667.31 × 920.05
4. Step 4: Simplify right side
   3,111.28x = 4,294,158.57
5. Step 5: Solve for x
   x = 4,294,158.57/3,111.28
6. Step 6: Final answer
   x = 1,380.19