Finding the Fourth Proportional to 111.42, 166.41 and 105.21

Step by Step Solution

1. Step 1: Write the proportion equation
   111.42 : 166.41 = 105.21 : x
2. Step 2: Convert to fraction form
   111.42/166.41 = 105.21/x
3. Step 3: Cross multiply
   111.42x = 166.41 × 105.21
4. Step 4: Simplify right side
   111.42x = 17,508.00
5. Step 5: Solve for x
   x = 17,508.00/111.42
6. Step 6: Final answer
   x = 157.14