Finding the Fourth Proportional to 111.20, 166.71 and 42.71

Step by Step Solution

1. Step 1: Write the proportion equation
   111.20 : 166.71 = 42.71 : x
2. Step 2: Convert to fraction form
   111.20/166.71 = 42.71/x
3. Step 3: Cross multiply
   111.20x = 166.71 × 42.71
4. Step 4: Simplify right side
   111.20x = 7,120.60
5. Step 5: Solve for x
   x = 7,120.60/111.20
6. Step 6: Final answer
   x = 64.03