Finding the Fourth Proportional to 111.17, 166.78 and 42.71

Step by Step Solution

1. Step 1: Write the proportion equation
   111.17 : 166.78 = 42.71 : x
2. Step 2: Convert to fraction form
   111.17/166.78 = 42.71/x
3. Step 3: Cross multiply
   111.17x = 166.78 × 42.71
4. Step 4: Simplify right side
   111.17x = 7,123.09
5. Step 5: Solve for x
   x = 7,123.09/111.17
6. Step 6: Final answer
   x = 64.07