Finding the Fourth Proportional to 111.92, 168.15 and 71.42

Step by Step Solution

1. Step 1: Write the proportion equation
   111.92 : 168.15 = 71.42 : x
2. Step 2: Convert to fraction form
   111.92/168.15 = 71.42/x
3. Step 3: Cross multiply
   111.92x = 168.15 × 71.42
4. Step 4: Simplify right side
   111.92x = 12,009.27
5. Step 5: Solve for x
   x = 12,009.27/111.92
6. Step 6: Final answer
   x = 107.30