Finding the Fourth Proportional to 111.25, 166.96 and 42.79

Step by Step Solution

1. Step 1: Write the proportion equation
   111.25 : 166.96 = 42.79 : x
2. Step 2: Convert to fraction form
   111.25/166.96 = 42.79/x
3. Step 3: Cross multiply
   111.25x = 166.96 × 42.79
4. Step 4: Simplify right side
   111.25x = 7,143.69
5. Step 5: Solve for x
   x = 7,143.69/111.25
6. Step 6: Final answer
   x = 64.21