Finding the Fourth Proportional to 111.09, 166.61 and 105.60

Step by Step Solution

1. Step 1: Write the proportion equation
   111.09 : 166.61 = 105.60 : x
2. Step 2: Convert to fraction form
   111.09/166.61 = 105.60/x
3. Step 3: Cross multiply
   111.09x = 166.61 × 105.60
4. Step 4: Simplify right side
   111.09x = 17,594.02
5. Step 5: Solve for x
   x = 17,594.02/111.09
6. Step 6: Final answer
   x = 158.38