Finding the Fourth Proportional to 111.49, 166.89 and 78.91

Step by Step Solution

1. Step 1: Write the proportion equation
   111.49 : 166.89 = 78.91 : x
2. Step 2: Convert to fraction form
   111.49/166.89 = 78.91/x
3. Step 3: Cross multiply
   111.49x = 166.89 × 78.91
4. Step 4: Simplify right side
   111.49x = 13,169.29
5. Step 5: Solve for x
   x = 13,169.29/111.49
6. Step 6: Final answer
   x = 118.12