Finding the Fourth Proportional to 111.16, 166.78 and 42.70

Step by Step Solution

1. Step 1: Write the proportion equation
   111.16 : 166.78 = 42.70 : x
2. Step 2: Convert to fraction form
   111.16/166.78 = 42.70/x
3. Step 3: Cross multiply
   111.16x = 166.78 × 42.70
4. Step 4: Simplify right side
   111.16x = 7,121.51
5. Step 5: Solve for x
   x = 7,121.51/111.16
6. Step 6: Final answer
   x = 64.07