Finding the Fourth Proportional to 111.91, 167.90 and 54.15

Step by Step Solution

1. Step 1: Write the proportion equation
   111.91 : 167.90 = 54.15 : x
2. Step 2: Convert to fraction form
   111.91/167.90 = 54.15/x
3. Step 3: Cross multiply
   111.91x = 167.90 × 54.15
4. Step 4: Simplify right side
   111.91x = 9,091.79
5. Step 5: Solve for x
   x = 9,091.79/111.91
6. Step 6: Final answer
   x = 81.24