Finding the Fourth Proportional to 111.98, 168 and 57.91

Step by Step Solution

1. Step 1: Write the proportion equation
   111.98 : 168 = 57.91 : x
2. Step 2: Convert to fraction form
   111.98/168 = 57.91/x
3. Step 3: Cross multiply
   111.98x = 168 × 57.91
4. Step 4: Simplify right side
   111.98x = 9,728.88
5. Step 5: Solve for x
   x = 9,728.88/111.98
6. Step 6: Final answer
   x = 86.88