Finding the Fourth Proportional to 111.15, 166.72 and 42.70

Step by Step Solution

1. Step 1: Write the proportion equation
   111.15 : 166.72 = 42.70 : x
2. Step 2: Convert to fraction form
   111.15/166.72 = 42.70/x
3. Step 3: Cross multiply
   111.15x = 166.72 × 42.70
4. Step 4: Simplify right side
   111.15x = 7,118.94
5. Step 5: Solve for x
   x = 7,118.94/111.15
6. Step 6: Final answer
   x = 64.05